Field guide to freshwater mussels of the Midwest

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APR 1 8

Field Guide

to

Freshwater Mussels
of the Midwest

Field Guide

to

Freshwater Mussels
of the Midwest

Kevin S. Cummings
Christine A. Mayer

Illinois Natural History Survey • Champaign

December 1992
Manual 5

Illinois Natural History Survey, Lorin I. Nevling, Chief
A Division of the Illinois Department of Energy and Natural Resources

Illinois Natural History Survey
Natural Resources Building
607 East Peabody Drive
Champaign, Illinois 61820

Printed by authority of the state of Illinois

81981— 3M— 12-92

second printing 556807 — 3M — 7-94

Editors: John Ballenot, Alison Fong Weingartner

About the authors: Kevin S. Cummings is an Associate Research
Biologist, and Christine A. Mayer is an Assistant Research Biologist
with the Illinois Natural History Survey, Center for Biodiversity, in
Champaign.

Partial funding for the preparation of this field guide was provided by the
U.S. Fish & Wildlife Service, Region 3 Office, Twin Cities, Minnesota;
the Illinois Department of Conservation, Division of Natural Heritage,
Springfield, Illinois; and the Mussel Mitigation Trust, Cincinnati, Ohio.
The Indiana Academy of Science provided partial funding for the second
printing of this manual.

Library of Congress Catalog Card Number: 92-83870

ISBN: 1-882932-00-5

Printed in the United States of America

Citation:

Cummings, K.S., and C.A. Mayer. 1992. Field guide to freshwater
mussels of the Midwest. Illinois Natural History Survey Manual 5.

194 pp.

ACES LIBRARY

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To the memory of Dr. Max R. Matteson ( 1909-1990 )
and field biologists everywhere

Contents

Foreword xi
Acknowledgments xiii
Introduction 1

Mussel Biology and Life History 1
Economic Importance 3
Conservation and Status 4
How to Collect Mussels 4

How to Use This Book 6

Explanation of Species Accounts 9

Text 9

Photographs 1 1
Maps 12

Glossary 1 6

Key to Freshwater Bivalves 18

Species Accounts 21
Subfamily Cumberlandinae

Spectaclecase Cumberlandia monodonta 22
Subfamily Ambleminae

Washboard Megalonaias nervosa 24
Pistolgrip Tritogonia verrucosa 26
Winged mapleleaf Quadrula fragosa 28
Mapleleaf Quadrula quadrula 30
Rabbitsfoot Quadrula cylindrica 32
Monkeyface Quadrula metanevra 34
Warty back Quadrula nodulata 36
Pimpleback Quadrula pustulosa 38
Threeridge Amblema plicata 40
Ebonyshell Fusconaia ebena 42
Long-solid Fusconaia subrotunda 44

Vlll

Mussels of the Midwest

Wabash pigtoe Fusconaia flava 46
Purple wartyback Cyclonaias tuherculata 48
Sheepnose Plethohasus cyphyus 50
White wartyback Plethohasus cicatricosus 52
Orange-foot pimpleback Plethohasus cooperianus 54
Clubshell Plewohema clava 56
Round pigtoe Pleurohema coccineum 58
Rough pigtoe Plewohema plenum 60
Ohio pigtoe Plewohema cordatum 62
Pyramid pigtoe Plewohema ruhrum 64
Elephant-ear Elliptio crassidens 66
Spike Elliptio dilatata 68
Cracking pearlymussel Hemistena lata 70
Pondhorn Uniomerus tetralasmus 72
Subfamily Anodontinae

Paper pondshell Utterhackia (-Anodonta) imhecillis 74
Flat floater Anodonta suhorhiculata 76
Giant floater Pyganodon (-Anodonta) grandis 78
Cylindrical papershell Anodontoides ferussacianus 80
Squawfoot Strophitus undulatus 82
Elktoe Alasmidonta marginata 84
Slippershell mussel Alasmidonta viridis 86
Rock-pocketbook Arcidens confragosus 88
Salamander mussel Simpsonaias amhigua 90
White heelsplitter Lasmigona complanata 92
Fluted-shell Lasmigona costata 94
Creek heelsplitter Lasmigona compressa 96
Subfamily Lampsilinae

Kidney shell Ptychohranchus fasciolaris 98
Threehom wartyback Ohliquaria reflexa 100
Fanshell Cyprogenia stegaria 102
Mucket Actinonaias ligamentina 104
Butterfly Ellipsaria lineolata 106
Hickorynut Ohovaria olivaria 108
Round hickorynut Ohovaria subrotunda 110
Ring pink Ohovaria retusa 112
Deertoe Truncilla truncata 1 14
Fawnsfoot Truncilla donaciformis 116

Contents

*

Scaleshell Leptodea leptodon 1 1 8
Fragile papershell Leptodea fragilis 120
Pink papershell Potamilus ohiensis 122
Pink heelsplitter Potamilus alatus 124
Bleufer Potamilus purpuratus 126
Fat pocketbook Potamilus capax 128
Lilliput Toxolasma parvus 130

Purple lilliput Toxolasma lividus 132
Texas lilliput Toxolasma texasensis 134
Black sandshell Li gumia recta 136
Pondmussel Li gumia subro strata 138
Ellipse V enustaconcha ellipsiformis 140
Rayed bean Villosa fabalis 142

Rainbow Villosa iris 144

t

Little spectaclecase Villosa lienosa 146
Yellow sandshell Lamp silis teres 148
Fatmucket Lampsilis siliquoidea 150
Higgins eye Lampsilis higginsi 152

Pink mucket Lampsilis abrupta 154

Plain pocketbook Lampsilis cardium 156
Pocketbook Lampsilis ovata 158
Wavy-rayed lampmussel Lampsilis fasciola 160
Snuffbox Epioblasma triquetra 162
Catspaw Epioblasma obliquata 1 64
Tubercled blossom Epioblasma torulosa 166
Northern riffleshell Epioblasma rangiana 168
Leafshell Epioblasma flexuosa 170
Round combshell Epioblasma personata 170
Tennessee riffleshell Epioblasma propinqua 170
Wabash riffleshell Epioblasma sampsonii 170
Fingernailclams and Peaclams (Family Sphaeriidae)
Asian Clam Corbicula fluminea 174
Zebra Mussel Dreissena polymorpha 176

Literature Cited 179

L

Additional Reading 181
Index 191

172

Foreword

This field guide to freshwater mussels is the fifth contribution to
a series that has been published at very irregular intervals. The
first in the series of Illinois Natural History Survey manuals was
published in 1936, and the fourth was issued nearly three and a
half decades ago. Previous volumes covered wildflowers, snails,
shrubs, and mammals.

Freshwater mussels are an interesting group of animals that
are not particularly well known by the public even though most
people exhibit an innate curiosity about them. Interest seems to
have waxed and waned in concert with the worth of their shells in
the commercial marketplace. Today the commercial exploitation
of mussels, particularly in the Mississippi and Ohio river drain¬
ages, is focused on shells to be used in the Japanese cultured
pearl industry. A nascent cultured pearl industry is only begin¬
ning in this country. Much of the current public interest in
mussels has been stimulated by the recently introduced zebra
mussel and the economic havoc it has created in some parts of its
new and rapidly expanding range in North America.

Professional biologists and informed amateurs alike have
recognized that freshwater mussels are particularly sensitive to
anthropogenic changes in our waterways. Thus, these mussels
can be used to judge stream quality or the degree of degradation.
It is especially meaningful to follow changes in mussel popula¬
tions over time. Because our predecessors assembled systematic
collections that have been carefully maintained and because of
the extensive efforts of the authors and others to reexamine
watersheds and relocate previously known localities for some
species, we have a better understanding of trends regarding
species distribution and populations. This knowledge offers little
encouragement or cause for contentment, however, because more
than half of the mussel species of the Midwest are threatened or

Xll

Mussels of the Midwest

endangered. No other major group of midwestem animals is so
imperiled.

Identification is usually the essential first step to unlocking
information about a species. For this reason, this field guide
includes color photographs and maps to assist the user in identi¬
fying mussels with a minimum of effort and specialized knowl¬
edge. I believe the user will find this approach a utilitarian one
that will lead to new knowledge of, and appreciation for, this
important group of organisms.

Champaign, Illinois
December 7, 1992

Lorin I. Nevling
Chief

Acknowledgments

This field guide was conceived in discussions with Chris Iverson
(formerly with the Indiana Department of Natural Resources),
and his help in getting the ball rolling is much appreciated.
Funding for the compilation of this book was provided by the
U.S. Fish and Wildlife Service (Region 3 Office), the Illinois
Department of Conservation-Division of Natural Heritage, and
the Mussel Mitigation Trust. The help and patience of Ron
Refsnider and Craig Johnson (USFWS), Glen Kruse and Mike
Sweet (IDOC), and Wayne Davis, John Marshall, and Bernard
Huff (MMT) is gratefully acknowledged. We would like to thank
Jeanine Berlocher, Art Bogan, Ron Cicerello, and Larry Page for
providing insightful comments, reviews, and helpful discussion
on various drafts of this field guide. We are especially grateful to
the curators and collection managers of the museums visited for
allowing us access to collections under their care. We thank our
family and friends for continued support and encouragement.
Finally, we extend special thanks to John Ballenot, Alison Fong
Weingartner, Bill Mayer, John Parker Sherrod, and Mike Jeffords
for assistance with editing, illustrations, and printing of the final
draft.

Introduction

Found on every continent except Antarctica, freshwater mussels
are most diverse in eastern North America, where they number
nearly 300 species. Their large shells make mussels the most
conspicuous mollusks in the waters of the Midwest.

Freshwater mussels (also referred to as clams, naiades, or
unionids) spend their entire life partially or wholly buried in mud,
sand, or gravel in permanent bodies of water. The vast majority
of species are found in streams, but a few are present in ponds or
lakes. Although they can be found in almost any type of stream
bottom, mussels are usually absent from, or rare in, areas of
shifting sand or deep silt.

Mussel Biology and Life History

In most species of freshwater mussels the sexes are separate.
Males release sperm into the water, the sperm enters the female
via the incurrent siphon, and the eggs are fertilized internally.

The fertilized eggs develop into an intermediate larval stage,
termed glochidia (singular, glochidium). The glochidia are stored
in the female’s gills, which function as a brood chamber as well
as a means for obtaining oxygen.

In the spring or summer, the glochidia are expelled into the
water to begin the parasitic phase of their life cycle (Figure 1).
The glochidia attach to an appropriate host, usually a fish, and
form numerous cysts. Some species, in fact, possess a “lure” for
attracting potential host fishes. Depending on the species of
mussel, the glochidia are either internal parasites, on the gills, or
external parasites, on the fins. Although some species are host-
specific, others can use a wide variety of fishes as hosts.

While encysted, the larvae change form and begin to
resemble adults. After metamorphosis, the small, young mussels
break free from the cysts and drop to the stream or lake bottom to
begin an independent life. The period of attachment varies from

2

Mussels of the Midwest

Figure 1. Generalized life cycle of freshwater mussels. Parasitic larval
mussels (glochidia) attach to a host and encyst; the host is usually a fish
(shown here: white crappie, Pomoxis annularis). After a few weeks the
glochidia transform into juveniles and drop from the host. Two different
strategies are employed: (1) internal hookless glochidia on the gills
(plain pocketbook, Lampsilis cardium , on the left) or (2) external hooked
glochidia on the fins (giant floater, Pyganodon [= Anodonta ] grandis, on
the right). (After U.S. Fish & Wildlife Service 1990).

about 1 to 25 weeks depending on the host, location of attach¬
ment, and water temperature.

Freshwater mussels continuously pump water through their
bodies. Water enters via the incurrent or branchial siphon and
exits via the excurrent or anal siphon. During this pumping
process, the mussel filters food from the water. The food consists
of detritus, which is organic matter found on the stream or lake
bottom, and plankton, composed of microscopic plants and
animals suspended in the water.

Introduction

3

Mussels are long-lived, with many species living more than
10 years and some reported to live more than 100 years. Thin-
shelled species (floaters and papershells, for example) grow
much faster than thicker-shelled species (threeridges and
mapleleafs, for example). In many species, the surface of the
shell has distinct black lines or ridges, which are believed to
represent winter rest periods. The rest periods, or growth rings,
are often used to estimate the age of a mussel.

Mussels are an important food source for many animals,
including muskrats, minks, otters, fishes, and some birds. Large
piles of freshly cleaned mussels, called middens, can be found
along the banks of a river or lake where muskrats are actively
foraging. These middens often contain many species and can be
one of the best places to find shells.

Economic Importance

Freshwater mussels were collected and used in various ways by
Native Americans, particularly the mound-building tribes of the
Midwest, long before Europeans set foot in North America.
Mussels were not only eaten but also used for tempering pottery
and for making utensils, tools, and jewelry (Baker 1930,
Matteson 1953).

In the late 1800s and early 1900s, enormous numbers of
freshwater mussels were harvested to make pearl buttons for
clothing, and button-making was a multimillion-dollar industry.
By 1912, nearly 200 factories were operating in towns such as
Muscatine, Keokuk, Peoria, and Beardstown (Coker 1919). The
pearl-button industry collapsed, however, with the invention and
widespread use of plastics in the 1940s and 1950s, and some
freshwater mussel populations subsequently recovered.

By the 1950s, the Japanese had found a new use and market
for freshwater mussels: cultured pearls for jewelry. Once har¬
vested, mussels are sorted and steamed or cooked out to remove
the soft parts. The shells are then cut and finished into beads for
insertion into an oyster to serve as nuclei for cultured pearls.
Today thousands of tons of mussel shells (particularly those of

4

Mussels of the Midwest

washboard and threeridge mussels) are harvested each year and
exported to Japan to supply the cultured pearl industry.

Conservation and Status

Freshwater mussels are one of the most endangered groups of
animals in North America. Surveys conducted over the past few
decades have documented significant declines in mussel popula¬
tions across the continent. Among the factors thought to be
responsible for the decline are overharvest; siltation of their
habitat from agriculture, poor land management, channelization,
and impoundments; competition from exotic species such as the
zebra mussel; and pollution by herbicides, pesticides, and other
chemicals. One result of the status surveys has been the designa¬
tion of many mussels as state-endangered or federally endangered
species. In the United States, 42 mussels are listed as federally
endangered or threatened, and another 70 have been proposed or
are candidates for listing (USFWS 1991a, 1991c).

How to Collect Mussels

Before collecting mussels it is advisable to contact the Depart¬
ment of Conservation or the Department of Natural Resources to
find out whether there are any restrictions and to obtain any
permits that may be required. Because of the rarity of many of
the native species, live mussels should never be collected without
prior permission. One can still build a nice collection by taking
only shells and returning all live mussels to the stream or lake.

Perhaps the best place to begin looking for shells is along the
bank of a medium-sized or large river when the water is at its
lowest level (usually July to September). Although a few species
can withstand some dessication, most are found in permanently
flowing streams or lakes that contain water year-round.

Mussels can be found in a variety of habitats but are most
abundant on shoals, where they live in gravel or a mixture of
sand, mud, and gravel. A wide variety of shells can often be
found along the shore in piles or “middens” left by muskrats or
raccoons. The simplest and possibly the most effective method of
collecting mussels is by hand-picking along the shore or in the

Introduction

5

stream. A small net bag or old potato sack makes a good con¬
tainer for holding shells in the field.

With a little practice, you can learn to see mussels in the
shallows of clear streams. Usually the only part visible is the
posterior end, with the incurrent and excurrent siphons protruding
from the stream bottom. A mussel can often be spotted at one end
of the meandering trail it leaves in the sand as it moves from
place to place.

For your specimens to have scientific as well as aesthetic
value, you need to keep accurate labels and records of field
observations. After specimens are collected, a label should be
made immediately and placed in the bag with the specimens; it
should include the following information: the name of the body
of water, road or bridge crossing, distance and direction from the
nearest town, the county and state, the date, and the name of the
collectors. Other information, such as water temperature, depth,
current velocity, bottom type, and time spent collecting, can be
recorded in a field notebook. Locality data should be written in
pencil or india ink on a good grade of label paper so the label will
not mold or disintegrate in the bag. Specimens without sufficient
locality data are essentially worthless, so it is extremely impor¬
tant to accurately label specimens.

Once collected, the shells should be cleaned with warm
water and a brush or teflon scrub pad to bring out the true colors
and other markings needed for identification. After cleaning,
locality data or a numbering system used to tie that specimen to a
particular locality should be written directly in the shell with a
pencil or india ink. If, after cleaning, you still have trouble
identifying your specimen, you can often send it to a specialist
for verification. Prior arrangements should be made with the
curator of a museum before sending specimens for identification.

By keeping well-organized and curated collections, many
amateurs have made significant contributions to malacology (the
study of mollusks) over the years. Most of the major museums of
the world contain donated private collections that are available
for study by specialists for years to come. See van der Schalie
(1941) for additional information about collecting shells.

How to Use This Book

This field guide is intended to help biologists, commercial
shelters, amateur naturalists, teachers, and students identify
freshwater mussels found in the streams and lakes of the Mid¬
west. It includes 78 species, over half of which are either rare,
threatened, endangered, or extinct. The species are arranged in
groups that approximate their systematic relationships; therefore,
similar-looking species will often, but not always, be grouped
together. An index to both the scientific and common names is
given in the back of the book. To get you started looking in the
right direction, a rough “key” to the major groups of freshwater
bivalves is given on pages 18 and 19.

The first thing to keep in mind when trying to identify a shell
is that freshwater mussels are extremely variable with respect to
coloration, shape, and size, both within and between species.
Although some species (especially the pigtoes) can be difficult to
tell apart without the aid of a specialist, nearly all of the mussels
in the Midwest can be identified using a combination of written
descriptions, photographs, and range maps. Perhaps the easiest
way to identify a mussel shell is to match your specimen to one
of the photographs. If you can’t find an exact match, pick the one
that looks the closest and refer to the text for the key characters
and similar species to eliminate those that look similar. Once a
tentative identification has been made, check the range map to
see if the species you have chosen is found in your area. When
the range map and photograph have been checked, read the full
species description to confirm your identification.

To identify specimens, you first need to know a little about
the basic anatomy of a mussel shell (Figure 2). Although this
field guide keeps jargon to a minimum, the descriptions include
technical terms used to describe anatomical features. A glossary
of terms commonly used in the text is given on pages 16 and 17.
Definitions are those used by Parmalee (1967) or Burch (1975).

How to Use This Book

7

DORSAL

Hinge

Posterior
ridge

Sulcus

Beak (umbo)

Pustules

POSTERIOR

ANTERIOR

Lateral

teeth

Interdentum

Pseudocardinal
teeth

Muscle scars

DM

Pallial line

VENTRAL

Figure 2. The major features of a freshwater mussel shell, as exemplified
by the mapleleaf ( Quadrula quadnda). The drawing shows the exterior
of the right valve (top) and the interior of the left valve (bottom).

Figure 2 is a drawing of a typical mussel shell and its salient
features. The anterior or front end of a mussel can be determined
by the position of the umbo and pseudocardinal teeth, both of
which are always located anteriorly. Among the features most

8

Mussels of the Midwest

often cited in the description of a mussel is the beak sculpture,
which consists of the ridges or raised lines found on the umbo.
Beak sculpture can vary from simple V-shaped lines to a series of
wavy, double-looped ridges.

The teeth are also important for identifying a shell. The
lateral teeth can be absent, straight, or curved; single or double;
smooth or serrated. The pseudocardinal teeth can be absent, small
and peglike, or prominent.

The depth of the beak cavity is often used to distinguish
between species. The beak cavity can be absent, shallow,
moderately deep, or deep.

External characters used to identify species include the
shape, number, and arrangement of pustules on the surface; the
presence or absence of a sulcus or shallow depression running
from the beaks to the ventral margin of the shell; and the promi¬
nence of the posterior ridge. In addition, the color of the perio-
stracum (outside) and nacre (inside) and the external texture of
the shell are often used to differentiate between species. Although
many species are highly variable with respect to color (both
outside and inside), others are relatively consistent in this regard.
Some mussels lacking obvious bumps, ridges, or pustules have a
characteristic rough or satinlike finish on the external surface.

The characters mentioned above are those most often used to
discern between species on the basis of the shell. Most other
anatomical features used in identification are associated with the
animal itself, often called the “soft parts.” Some of the most
often used features include the size and shape of the marsupium,
glochidia, labial palps, and siphons. References to these features
can be found in more comprehensive books on mussels (e.g.,
Baker 1928, Parmalee 1967, Oesch 1984).

Explanation of Species Accounts

Each species account has three components: text, photograph,
and range map. A brief explanation of these components follows.

Text

Each account begins by listing a common name as well as the
scientific name of the mussel. The names in this book are largely
those used in American Fisheries Society Special Publication 16,
Common and Scientific Mantes of Aquatic Invertebrates from the
United States and Canada: Mollusks (Turgeon et al. 1988).
Exceptions to this list are that subspecies are not recognized and
a few modifications have been made to reflect changes since the
publication of the 1988 list (Hoeh 1990, Cummings and
Berlocher 1990, Bogan personal communication). The text in
each species account is divided into the following sections: other
common names, key characters, similar species, description,
habitat, and status.

Other common name(s). Common names given to mussels
are regional and can vary considerably from place to place. Some
of the common names frequently encountered in the literature or
in the field are included in this section. Differences in common
names can create problems for the governmental resource
agencies responsible for managing mussels. The proper identifi¬
cation and recording of species is essential for accurate data
gathering and analysis of commercial harvest statistics or
sightings of endangered species.

Key characters. This section summarizes a few of the more
prominent features used to identify each species. The key
characters may be enough to identify a particular specimen, but
in most instances you should read over the entire description to
confirm your identification.

Similar species. A list of those species similar in color,
shape, and size is included for comparison, when some doubt as

10

Mussels of the Midwest

to the identity remains. The species listed may or may not be
closely related.

Description. The descriptions are for shells only and do not
include any of the characteristic features of the animal itself. The
first paragraph describes the external parts of the shell, including
coloration, shape, size, surface features, and thickness. A near¬
maximum adult size is also given in inches and its centimeter
equivalent; most specimens will be somewhat smaller. The
second paragraph covers internal features, including the
pseudocardinal teeth, lateral teeth, depth of the beak cavity, and
nacre color.

Habitat. Mussels vary considerably with respect to their
habitat preferences. Some are restricted to a specific habitat type
(for example, small creeks), whereas others can be found in
almost any permanent body of water. Each account lists the size
of the stream (headwater, creek, small, medium, or large river) in
which the species is typically found. The habitat descriptions also
include statements on the composition of the bottom (for ex¬
ample, silt, mud, sand, or gravel) and, occasionally, water flow.

Status. Over half of the species in this field guide are
considered rare, threatened, or endangered by at least one of the
states in the Midwest. Each account gives a general statement
regarding the species distribution and abundance, often followed
by information on its status in individual states. Not all states use
the same criteria in determining or labeling special-status species.
For example, Missouri uses “rare” as opposed to “threatened” for
those species that are likely to become endangered if conditions
worsen.

This field guide also employs several categories used by the
U.S. Department of the Interior. An “endangered” species as
defined by the federal government is any species that is in danger
of becoming extinct throughout all or a major portion of its range.
A “threatened” species is one that is likely to become an endan¬
gered species within the foreseeable future throughout all or a
major portion of its range (USFWS 1991b). Federal candidate
species are divided into several categories (USFWS 1990b). A
“Category 1” classification is used for species for which the U.S.

Explanation of Species Accounts

1 1

Fish and Wildlife Service has “enough substantial information on
biological vulnerability and threat(s) to support proposals to list
them as endangered or threatened species/' Species for “Category
2” status are those for which there is some evidence for vulner¬
ability but not enough data for them to be listed as endangered or
threatened. “Category 3A” species are those that the Fish and
Wildlife Service considers extinct.

Photographs

The photographs in this field guide are of specimens in the
mollusk collections of the Illinois Natural History Survey,
Champaign (INHS), and the University of Illinois Museum of
Natural History, Urbana (UIMNH). The shells were selected
because they were considered representative of their species. In
cases in which males and females are noticeably different, both
are shown. Each plate shows the right valve, so that the front or
anterior end is always to the right. The photos are not to scale,
but much larger species are usually shown somewhat larger on
the page. The length of each specimen shown is given in the
photo caption.

Although this field guide is intended for use in identifying
freshwater mussels, we have included photographs of representa¬
tives of some of the other bivalves found in the Midwest: a
representative of the native fingernailclam or peaclam family
(Sphaeriidae), the introduced Asian clam ( Corbicula ), and the
recently introduced zebra mussel ( Dreissena ). Both the Asian
clam and zebra mussel are prolific breeders and have caused
severe problems for industries and municipalities that utilize lake
or river water by clogging intake lines and blocking the flow of
water. The zebra mussel in particular is having a major impact on
our native mussel species. Zebra mussels will attach themselves
to any firm object, including freshwater mussels. A colony of
zebra mussels attached to a freshwater mussel will impede the
flow of water, food, and oxygen and will eventually kill it.
Researchers are investigating ways to control these unwanted
pests without further endangering other species found in our
rivers and lakes.

12

Mussels of the Midwest

Maps

Knowing where a specimen was collected can be very helpful
when trying to identify it. The range maps in this field guide
cover the Ohio, Mississippi, and Red river drainages in Minne¬
sota, Wisconsin, Iowa, Missouri, Illinois, Indiana, and Ohio and
part of the upper Great Lakes drainage (Figure 3). Mussels
endemic to the Ozarks or those that reach the northern limit of
their range in southern Missouri are not included but can be
found in Missouri Naiades. A Guide to the Mussels of Missouri
(Oesch 1984).

Many of the species found in the Midwest are also present in
the Great Lakes and their tributaries. Unfortunately, specific
distributional information is unavailable, and maps depicting the
range of species found in the Great Lakes drainage in Indiana,
Michigan, Minnesota, and Ohio are not included. However,
nearly all of the mussels found in the Great Lakes drainage are
described and illustrated in this book.

The maps on the following pages show the approximate
historic ranges of mussels in the Midwest. The maps are not
meant to be comprehensive and will undoubtedly change as

Figure 3. The area covered by this field guide.

Explanation of Species Accounts

13

additional data are collected. Within these ranges, gaps in
distribution may occur in areas not suitable for mussels. For
example, the cylindrical papershell occurs throughout much of
the Midwest but is found only in small creeks and the headwaters
of large rivers; it is therefore absent from many of the streams
within its range.

The information used to prepare the maps was taken from
various sources. The Illinois and Indiana portions of the maps
were compiled from examination of more than 85,000 specimens
in the following collections: Academy of Natural Sciences,
Philadelphia; Chicago Academy of Sciences; Field Museum of
Natural History; Illinois Natural History Survey; Museum of
Comparative Zoology, Harvard; Ohio State University Museum
of Zoology; University of Illinois Museum of Natural History;
University of Michigan Museum of Zoology; and the National
Museum of Natural History of the Smithsonian Institution. Range
maps for the other states were compiled from the following
publications or technical reports:

Bright, R.C., E. Plummer, and D. Olsen. 1989. A survey of the
mussels of the Zumbro River drainage, southeastern Minnesota.
Bell Museum of Natural History, University of Minnesota. 27 pp.
+ illustrations and appendices.

Bright, R.C., C. Gatenby, D. Olsen, and E. Plummer. 1990. A
survey of the mussels of the Minnesota River, 1989. Bell
Museum of Natural History, University of Minnesota. 36 pp. +
illustrations and appendices.

Clarke, A.H. 1981. The Tribe Alasmidontini (Unionidae:
Anodontinae), Part I: Pegias , Alasmidonta , and Arcidens.
Smithsonian Contributions to Zoology No. 326. 101 pp.

- 1985. The Tribe Alasmidontini (Unionidae:

Anodontinae), Part II: Lasmigona and Simpsonaias. Smithsonian
Contributions to Zoology No. 399. 75 pp.

14

Mussels of the Midwest

Cvancara, A.M. 1970. Mussels (Unionidae) of the Red River
Valley in North Dakota and Minnesota, U.S.A. Malacologia
10(l):57-92.

Davis, M. 1987. Freshwater mussels (Mollusca: Bivalvia:
Unionidae) of the Cannon River drainage in southeastern
Minnesota. Minnesota Department of Natural Resources. 23 pp.

+ appendices.

Dawley, C. 1947. Distribution of aquatic mollusks in Minnesota.
American Midland Naturalist 38(3):67 1-697.

Frest, T.J. 1987. Mussel survey of selected interior Iowa streams.
University of Northern Iowa. Final Report to Iowa Department of
Natural Resources and U.S. Fish & Wildlife Service. 354 pp.

Johnson, R.I. 1980. Zoogeography of North American Unionacea
(Mollusca: Bivalvia) north of the maximum Pleistocene glacia¬
tion. Bulletin of the Museum of Comparative Zoology, Harvard
University 1 49(2):77— 1 89.

Mathiak, H.A. 1979. A river survey of the unionid mussels of
Wisconsin 1973—1977. Sand Shell Press, Horicon, Wisconsin.

75 pp.

Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of
Missouri. Missouri Department of Conservation, Jefferson City,
Missouri. 270 pp.

Stansbery, D.H., K.E. Newman, K.G. Borror, and C.B. Stein.
1985. Literature records of bivalve mollusks of the Muskingum
River system, Ohio. Ohio State University Museum of Zoology
Reports 1985(1): 1-472.

Watters, G.T. 1988. The naiad fauna of selected streams in
Ohio. Ohio State University. Final Report to Ohio Department of
Natural Resources. 440 pp.

Explanation of Species Accounts

15

- 1992. Distribution of the Unionidae in South Central

Ohio. Malacology Data Net 3( l^l):56-90.

Williams, J.C., and G.A. Schuster. 1989. Freshwater mussel
investigations of the Ohio River. Mile 317.0 to mile 981.0.
Kentucky Department of Fish and Wildlife Resources, Division
of Fisheries. 57 pp.

Wilson, C.B., and E. Danglade. 1914. The mussel fauna of
central and northern Minnesota. U.S. Bureau of Fisheries
Document No. 803. 26 pp. + 1 map.

Glossary

Knowledge of the following terms is important for understanding
the species accounts.

Anterior end — the shorter end of the shell as measured from
the umbo; also considered the front end
Beak — the raised part of the dorsal margin of the shell; also
called the umbo

Beak cavity — the depression or pocket on the inside of each
valve leading into the beak

Beak sculpture — the raised loops, ridges, or bumps on the
umbo

Chevron — a V-shaped marking

Compressed — flattened or pressed together laterally

Concentric — having a common center

Distal — away from the center or origin

Dorsal — referring to the top part of the shell where the hinge is
located

Elliptical — having the form of an ellipse, or oval
Elongate — long or extended
Extirpated — locally extinct

Growth lines — darkened lines on the surface of the shell
indicating periods of rest during growth
Hinge — the elastic part of the shell that unites the valves along
the top of the shell
Inflated — swollen or expanded

Interdentum — a flattened area between the pseudocardinal and
lateral teeth

Iridescent — exhibiting rainbow colors
Lateral teeth — the elongated teeth along the hinge line of the
shell

Left valve — the left half of the shell when the dorsal edge or
hinge is facing up and the anterior end is directed forward
(away from the collector)

Glossary

17

Nacre — the interior layer of the shell, usually white, pink,
salmon, or purple and iridescent
Oblong — having the shape of or resembling a rectangle or
ellipse

Ovate — egg-shaped

Pallial line — a linear depression on the inside of the shell
Periostracum — the outside layer or covering of the shell

Plications — folds

Posterior end — the longer end of the shell as measured from
the umbo; also considered the back end; also the end with the
siphons, usually sticking above the stream bottom
Posterior ridge — the ridge on the back half of the valve
running from the umbo to the posterior ventral edge
Posterior slope — the area along the dorsal part of the shell
between the posterior ridges of the valves
Pseudocardinal teeth — the triangular, often serrated, teeth
located on the anterior-dorsal part of the shell
Pustule — a bump or raised knob on the outside surface of the
shell

Quadrate — square

Right valve — the right half of the shell when the dorsal edge or
hinge is facing up and the anterior end is directed forward
(away from the collector)

Serrated — notched or grooved

Shell margin — the circumference of a valve outline when laid
flat; also known as the edge
Solid — thick or heavy
Striated — marked with lines or grooves
Sulcus — a shallow depression or furrow on the outside surface
of the shell

Truncate — having the end shortened or squared off
Tubercle — a pointed, rounded, or knoblike projection on the
shell

Umbo — the inflated dorsal part of the shell; also called the beak
Valve — one of the two halves of the shell
Ventral — referring to the bottom edge of the shell

J

Key to Freshwater Bivalves

Freshwater Mussels

Shell elongated, thin to moderately thick. Beak sculpture concen¬
tric. Surface of the shell dark brown to black. Pseudocardinal and
lateral teeth poorly developed; present only as a thickened ridge.
Sexual differences in the shell indistinct. Found in areas of
reduced flow (around large boulders) in large rivers with swift
currents . Cumberlandinae pp. 22-23

Shell usually thick and solid. Beak sculpture generally indistinct.
Surface of the shell brown, chestnut, or tan, rays or bands greatly
reduced or absent. Pseudocardinal and lateral teeth usually well
developed. Sexual differences in the shell indistinct. Most often
found in streams, but occasionally present in lakes or large
impoundments . Ambleminae pp. 24-73

Shell thin, more or less elongated. Beak sculpture usually double-
looped, occasionally concentric. Surface of the shell green,
greenish brown, or black with or without fine green rays. Pseudo¬
cardinal and lateral teeth absent, reduced, or poorly developed.
Sexual differences in the shell indistinct. Found in ponds, lakes,
or the quiet-water areas of streams . Anodontinae pp. 74-97

Shell relatively thin to moderately thick, rounded or oval to
elongate. Beak sculpture generally double-looped but often
indistinct. Surface of the shell mostly light yellow or tan with
brightly colored rays or bands. Pseudoeardinal and lateral teeth
usually well-developed. Sexual differences in the shell appar¬
ent — squared or truncated posteriorly in females, bluntly pointed
posteriorly in males. Found in streams, occasionally in lakes or
other impoundments . Lampsilinae pp. 98-171

Key to Freshw ater Bivalves

19

Fingernailclams and Peaclams

Shell relatively small, whitish or cream-colored. Surface of the
shell covered by numerous, very fine concentric rows of elevated
lines (striae). Right valve has one cardinal tooth and two pairs of
lateral teeth. Left valve has two cardinal teeth and two lateral
teeth . Sphaeriidae pp. 172-173

Asian Clam

Shell small (most under 2 inches), moderately thick, rounded.
Surface of the shell yellowish brown to black, with numerous,
evenly spaced, concentric, elevated ridges. Three cardinal teeth in
each valve located below the umbo; two sets of serrated lateral
teeth in each valve, paired on each side of the umbo in the right
valve, single on each side in the left. Introduced into western
North America in the 1920s and 1930s and spreading throughout
the United States . Corbiculidae pp. 174-175

Zebra Mussel

Shell small (most under 1 inch), moderately thick, triangular, and
more or less elongated. Surface variably banded with black or
brown and cream stripes. Introduced into the Great Lakes in the
1980s and spreading to large rivers and lakes throughout the
United States . Dreissenidae pp. 176-177

22

Mussels of the Midwest

Spectaclecase

Cumberlandia monodonta (Say, 1829)

Other common names None.

Key characters Elongate shell, usually pinched in the middle,
dark brown to black, with poorly developed teeth.

Similar species Spike, black sandshell, salamander mussel.

Description Shell oblong, elongate, and compressed. Anterior
and posterior ends rounded. Ventral margin usually arched or
pinched, occasionally straight. Shell thin in young, becoming
thicker in older individuals. Umbos only slightly elevated above
the hinge line. Beak sculpture, when visible, of three or four
heavy ridges. Surface of shell smooth to somewhat rough, brown
in young shells, becoming dark brown to black and rayless with
age. Length to 8 inches (20.3 cm).

Pseudocardinal teeth small, tubercular; one in each valve in
young individuals. Lateral teeth poorly developed or absent. Beak
cavity moderately shallow. Nacre white, iridescent in young
individuals and on the posterior fourth of shell in adults.

Habitat Large rivers with swiftly flowing water, among boul¬
ders in patches of sand, cobble, or gravel in areas where current is
reduced.

Status Widely distributed but absent from many areas where it
formerly occurred. Federal Candidate (Category 2). Extirpated
from Ohio and possibly Indiana. Endangered in Illinois, Iowa,
and Wisconsin. Watch List in Missouri.

Subfamily Cumberlandinae

23

Cumberlandia monodonta, INHS 7445. Green River, Warren County,
Kentucky. Length: 5.2 inches (13.2 cm).

24

Mussels of the Midwest

Washboard

Megalonaias nervosa (Rafinesque, 1820)

Other common names Bald-pate, board.

Key characters Large, black shell, heavily sculptured with V-
shaped ridges in the front and large folds on the sides and back,
particularly in smaller shells.

Similar species Threeridge, rock-pocketbook.

Description Shell large, thick, slightly elongate, rectangular, and
compressed to moderately inflated. Anterior end rounded,
posterior end truncated. Dorsal margin straight, ventral margin
straight to slightly curved. A small wing with several ridges
present behind the umbo (most evident in small shells, becoming
indistinct in larger shells). Umbos not elevated above the hinge
line. Beak sculpture of prominent double-looped ridges, enlarg¬
ing into bumps and folds on the posterior ridge. Upper shell with
irregularly shaped tubercles or V-shaped ridges (covering the
shell of juveniles). A series of large folds present on the posterior
half of the shell. Periostracum rayless, light brown in juveniles,
dark brown or black in adults. Length to 1 1 inches (27.9 cm).

Pseudocardinal teeth well developed and serrated; two in the
left valve, one in the right (occasionally with a small tooth on
either side). Lateral teeth straight to slightly curved; two in the
left, one in the right. Beak cavity fairly deep. Nacre white, often
with purple or copper-colored blotches, iridescent posteriorly.

Habitat Primarily large rivers with a good current; occasionally
medium-sized streams in mud, sand, or gravel.

Status Commercial species. May be common in its preferred
habitat. Endangered in Ohio.

Subfamily Ambleminae

25

Megalonaias nervosa , INHS 12568. East Fork White River, Lawrence
County, Indiana. Length: 5.0 inches (12.7 cm).

26

Mussels of the Midwest

Pistolgrip

Tritogonia verrucosa (Rafinesque, 1820)

Other common names Buckhorn, peanut, turkey wing.

Key characters Elongate, posterior wing with folds, sides of the
shell covered with pustules.

Similar species Rabbitsfoot.

Description Shell thick, elongate, and compressed. Anterior end
rounded, posterior end squared or truncated in males, elongate
and rounded in females. Dorsal margin straight to slightly curved,
ventral margin usually arched. Umbos low, only slightly elevated
above the hinge line. Beak sculpture of a series of pronounced
ridges continuing down the sides. Entire shell (except the
rounded posterior ridge of the female) covered with irregularly
sized and arranged pustules. Periostracum green or light brown,
becoming dark brown to black in older shells. Length to 8 inches
(20.3 cm).

Pseudocardinal teeth large, serrated, and well developed; two
in the left valve, one in the right (occasionally with a small tooth
on either side). Lateral teeth long, straight, and striated; two in
the left valve, one in right. Beak cavity deep. Nacre white,
iridescent posteriorly.

Habitat Medium to large rivers in mud, sand, or gravel.

Status Widespread but relatively uncommon. Endangered in
Iowa. Threatened in Wisconsin.

Subfamily Ambleminae

27

Tritogonia verrucosa , INHS 8935. Spoon River, Peoria County, Illinois.
Length: 5.4 inches (13.7 cm).

28

Mussels of the Midwest

Winged mapleleaf

Quadrula fragosa (Conrad, 1835)

Other common names False mapleleaf, hickory nut shell.

Key characters Fairly thick shell with well-developed teeth.
Squared in outline, an obvious wing behind the umbo with wide
radiating ridges. Lateral surface of the shell with two rows of
pustules separated by a sulcus or furrow.

Similar species Mapleleaf, wartyback.

Description Shell quadrate or square, thick, and moderately
inflated. Anterior end rounded, posterior end squared or trun¬
cated. Dorsal margin straight, ventral margin curved in the
anterior half, arched posteriorly. A pronounced wing present
posterior to the umbo, with radiating rows of pustules or ridges.
Umbos small and elevated above the hinge line. Beak sculpture
of two rows of raised bumps or nodules that continue downward
on the surface of the shell, separated by a furrow or sulcus.
Periostracum variable, from yellowish green to light brown with
faint rays in small shells, becoming greenish brown, chestnut, or
dark brown in larger individuals. Length to 4 inches (10.2 cm).

Pseudocardinal teeth well developed, serrated; two in the left
valve, one in the right. Lateral teeth striated, fairly long, and
straight; two in the left valve, one in the right. Beak cavity very
deep. Nacre pearly white, iridescent posteriorly.

Habitat Medium to large rivers in mud, sand, or gravel.

Status Federally Endangered. Only known extant population in
the Midwest occurs in Wisconsin.

30

Mussels of the Midwest

Mapleleaf

Quadrula quadrula (Rafinesque, 1 820)

Other common name Stranger.

Key characters Fairly thick shell with well-developed teeth.
Squared in outline, lateral surface with two rows of pustules
separated by a sulcus.

Similar species Winged mapleleaf, pimpleback, purple
pimpleback, monkeyface, wartyback.

Description Shell quadrate to rounded, thick, and somewhat
inflated. Anterior end rounded, posterior end squared or trun¬
cated. Dorsal margin straight, ventral margin curved in the
anterior half, straight or arched posteriorly. Umbos small and
only slightly elevated above the hinge line. Beak sculpture of two
rows of raised bumps or nodules that continue downward on the
surface of the shell, separated by a furrow or sulcus. Rows of
ridges or pustules on either side of sulcus and on posterior slope,
rest of surface usually smooth. Periostracum variable, from
yellowish green to light brown with faint rays in small shells,
becoming greenish brown, chestnut, or dark brown in larger
individuals. Length to 4 inches (10.2 cm).

Pseudocardinal teeth well developed, serrated; two in the left
valve (occasionally with a small tooth on either side), one in the
right. Lateral teeth striated, fairly long, and straight; two in the
left valve, one in the right. Beak cavity deep. Nacre pearly white,
iridescent posteriorly.

Habitat Medium to large rivers and reservoirs with a mud, sand,
or gravel bottom.

Status Widespread and common. Commercial species.

32

Mussels of the Midwest

Rabbitsfoot

Quadrula cylindrica (Say, 1817)

Other common names Smooth cob shell, spectaclecase mussel.

Key characters Elongate, rectangular shell with pustules and V-
shaped markings.

Similar species Monkeyface, pistolgrip.

Description Shell rectangular, elongate (about three times as
long as high), thick, and compressed to moderately inflated.
Anterior end rounded, posterior end squared or truncated. Dorsal
and ventral margins parallel. Umbos low, only slightly elevated
above the hinge line. Beak sculpture consists of two rows of
knobs or ridges that continue down the lateral surface of the shell.
Surface of the shell usually rough, with numerous tubercles on
the anterior end and a series of large pustules or knobs along the
posterior ridge. Periostracum green or light brown (darker in
older shells) with yellow zigzag or chevron-shaped markings on
the shell. Length to 5 inches (12.7 cm).

Pseudocardinal teeth serrated and well developed; two in the
left valve, one in the right. Lateral teeth very long and straight;
two in the left valve, one in the right. Beak cavity deep. Nacre
pearly white, iridescent posteriorly.

Habitat Medium to large rivers in mixed sand and gravel.

Status Rare throughout its range. Endangered in Illinois,

Indiana, Missouri, and Ohio.

Subfamily Ambleminae

33

Quadrula cylindrical INHS 6974. North Fork Vermilion River, Vermil¬
ion County, Illinois. Length: 2.2 inches (5.6 cm).

34

Mussels of the Midwest

Monkeyface

Quadrula metanevra (Rafinesque, 1820)

Other common name Knobbed rock shell.

Key characters Rounded or squared shell with large knobs
along the posterior ridge and a distinct indentation on the
posterior margin that looks like a chimpanzee in profile. Distinc¬
tive zigzag markings on the shell (may be lacking in older
individuals).

Similar species Rabbitsfoot, mapleleaf, pimpleback, wartyback.

Description Shell thick, rounded or rectangular, and moderately
inflated. Anterior end rounded, posterior end squared or truncated
and indented in the middle. Dorsal margin straight, area behind
the umbos flattened into a wing, ventral margin curved. Umbos
elevated above the hinge line. Beak sculpture of pronounced
ridges or knobs that continue down the posterior ridge to the
ventral margin of the shell. Shell rough, with numerous pustules
on the anterior half and behind the umbos and a row of large
knobs along the posterior ridge. Periostracum green or light
brown (darker in older shells) with yellow zigzag or chevron¬
shaped markings on the shell. Length to 4 inches (10.2 cm).

Pseudocardinal teeth serrated and well developed; two in the
left valve, one in the right (occasionally with a small tooth on
either side). Lateral teeth short, heavy, serrated and straight; two
in the left valve, one in the right. Beak cavity deep. Nacre pearly
white, iridescent posteriorly.

Habitat Medium to large rivers in gravel or mixed sand and
gravel.

Status Relatively uncommon but may be locally abundant.
Endangered in Ohio. Threatened in Wisconsin.

Subfamily Ambleminae

35

Quadrula metanevra, INHS 6221. Wabash River, Tippecanoe County,
Indiana. Length: 2.4 inches (6.1 cm).

36

Mussels of the Midwest

Wartyback

Quadrula nodulata (Rafinesque, 1820)

Other common names Two-horned pocketbook, winged
pimpleback, pimpleback, nodule shell, winged orb shell.

Key characters Rounded shell with two rows of paired knobs or
pustules on the posterior half of the shell; no sulcus.

Similar species Pimpleback, mapleleaf, monkeyface, threehorn
wartyback.

Description Shell relatively thick, rounded, and inflated.
Anterior end rounded, posterior end squared or truncated. Dorsal
margin straight, area behind the umbos flattened into a small
wing, ventral margin broadly rounded. Umbos rounded and
elevated above the hinge line. Beak sculpture, if visible, of small
ridges. Shell smooth except for two rows of knobs, usually
occurring in pairs, that extend from the umbos to the ventral
margin of the shell. No sulcus. Periostracum rayless and uni¬
formly yellowish green or light brown, becoming darker with
age. Length to 3 inches (7.6 cm).

Pseudocardinal teeth serrated and well developed; two in the
left valve, one in the right (occasionally with a small tooth on
either side). Lateral teeth short, heavy, serrated and straight to
somewhat curved; two in the left valve, one in the right. Beak
cavity deep. Nacre pearly white, iridescent posteriorly.

Habitat Large rivers or in the lower sections of medium-sized
rivers in sand or fine gravel.

Status Uncommon, but locally abundant. Endangered in Ohio.
Threatened in Wisconsin. Rare in Missouri.

Subfamily Ambleminae

37

Quadrula nodulata, INHS 10227. Mississippi River, Scott County, Iowa.
Length: 1.9 inches (4.8 cm).

38

Mussels of the Midwest

Pimpleback

Quadrula pustulosa (Lea, 1831)

Other common names Wartyback, warty pigtoe.

Key characters Rounded shell, a green stripe on the umbo,
usually densely covered with pustules. Beak cavity deep and
open, not compressed as in the purple wartyback.

Similar species Orange-foot pimpleback, purple wartyback,
wartyback, mapleleaf.

Description Shell thick, rounded, and compressed to moderately
inflated. Anterior end rounded, posterior end rounded to some¬
what truncated. Dorsal margin straight, ventral margin curved.
Umbos elevated above the hinge line. Beak sculpture, when
present, of two or three very small ridges. Shell normally smooth
on the anterior half; posterior half or two-thirds covered with
pustules or bumps (rarely absent). Periostracum yellowish-green
to light brown in small shells, becoming chestnut to dark brown
in older shells. A broad, broken green ray present on the umbo
extending toward the ventral margin, may be indistinct on older
shells. Length to 4 inches (10.2 cm).

Pseudocardinal teeth serrated and well developed; two in the
right valve, one in the left (occasionally with a small tooth on
either side). Lateral teeth heavy, serrated, and straight to slightly
curved; two in the left valve, one in the right. Beak cavity deep.
Nacre pearly white, iridescent posteriorly.

Habitat Medium to large rivers in mud, sand, or gravel.

Status Widespread and relatively common. Commercial species.

Subfamily Ambleminae

39

Quadrula pustulosa, INHS 1 1704. Iroquois River, Kankakee County,
Illinois. Length: 2.2 inches (5.6 cm).

40

Mussels of the Midwest

Threeridge

Amblema plicata (Say, 1817)

Other common names Blue-point, purple-tip, fluter.

Key characters Elongate or rounded shell with ridges or folds
on the posterior half. No sculpturing on the anterior end, espe¬
cially near the umbo.

Similar species Washboard, rock-pocketbook.

Description Shell thick, elongate or rounded, and compressed to
inflated. Anterior end rounded, posterior end rounded or bluntly
pointed. Dorsal margin straight, ventral margin straight to curved.
Umbos low, equal to or slightly elevated above the hinge line.
Beak sculpture of three or four ridges usually seen only in young
shells. Shell smooth on the anterior third, with three or more
roughly parallel ridges or folds on the posterior two-thirds. Shells
from large rivers generally more inflated and without as many
folds or wrinkles as those found in smaller streams. Periostracum
yellowish green, light brown, or green in juveniles, becoming
dark green, brown, or black in older shells. Length to 7 inches
(17.8 cm).

Pseudocardinal teeth serrated and well developed; two in the
left valve, one in the right (occasionally with a small tooth on
either side). Lateral teeth serrated and straight to slightly curved;
two in the left valve, one in the right. Beak cavity medium to
deep. Nacre pearly white, frequently stained, iridescent posteri¬
orly. Some individuals with a purple tint on the posterior end.

Habitat Small to large rivers and impoundments in mud, sand,
or gravel.

Status Widespread and common throughout most of its range.
Apparently declining in some smaller streams. Commercial
species.

42

Mussels of the Midwest

Ebonyshell

Fusconaia ebena (Lea, 1831)

Other common names None.

Key characters Round, heavy, thick, brown or black shell
without rays or pustules. Beak cavity very deep.

Similar species Long-solid, hickorynut, round hickorynut, ring
pink, pigtoes ( Fusconaia and Pleurobema).

Description Shell solid, heavy, rounded or oval, and inflated.
Anterior end rounded, posterior end rounded or bluntly pointed.
Dorsal margin slightly rounded, ventral margin curved, occasion¬
ally straight. Umbos low, inflated, about even with hinge line and
curved downward. Beak sculpture consists of a few very weak
ridges, apparent only in extremely small shells. Shell smooth
with slightly elevated ridges indicating periods of growth.
Periostracum rayless, light brown in young shells, becoming dark
brown to black in older individuals. Length to 4 inches (10.2 cm).

Pseudocardinal teeth very heavy and well developed; two in
the left valve, two in the right. Lateral teeth serrated and curved;
two in the left valve, one in the right. Beak cavity very deep.
Nacre pearly white, iridescent posteriorly.

Habitat Large rivers in sand and gravel.

Status Endangered in Missouri and Wisconsin. Threatened in
Ohio. Species of Special Concern in Illinois and Minnesota.

Subfamily Ambleminae

43

Fusconaia ebena, INHS 2656. Ohio River, Pulaski County, Illinois.
Length: 2.9 inches (7.4 cm).

44

Mussels of the Midwest

Long-solid

Fusconaia subrotunda (Lea, 1831)

Other common names Round-solid, pigtoe.

Key characters Smooth, elongate, and solid shell; beak cavity
very deep, green rays on the umbo.

Similar species Ebonyshell, pigtoes ( Fusconaia and
Pleurobema).

Description Shell relatively large, solid, elongate, oval or
elliptical, and moderately inflated. Anterior end rounded,
posterior end rounded or bluntly pointed. Dorsal margin and
ventral margins straight to slightly curved. Umbos low and
directed forward. Shell smooth, light brown, becoming dark
brown to black in adults. Fine green rays present on juveniles and
the umbos of older shells. Length to 5 inches (12.7 cm).

Pseudocardinal teeth large and well developed; two in the
left valve, one in the right (occasionally with a small tooth on
either side). Lateral teeth large and straight; two in the left valve,
one in the right. Beak cavity very deep. Nacre white, iridescent
posteriorly.

Habitat Large rivers in gravel.

Status Endangered in Indiana and Ohio. Extirpated from
Illinois.

46

Mussels of the Midwest

Wabash pigtoe

Fusconaia flava (Rafinesque, 1820)

Other common name Pigtoe.

Key characters Triangular shell with a shallow sulcus usually
present on the side, rough clothlike periostracum, deep beak
cavity.

Similar species All other pigtoes (. Fusconaia and Pleurohema).

Description Shell highly variable, moderately thick, triangular,
and compressed (creeks and small rivers) to inflated (large
rivers). Anterior end rounded, posterior end bluntly pointed.
Dorsal margin straight, ventral margin curved anteriorly and
straight or slightly arched posteriorly. Umbos low to moderately
elevated and inflated. Beak sculpture of a few weak ridges
apparent only in very small shells. A wide, shallow depression or
sulcus usually present. Shell with a clothlike texture, yellowish
brown, with faint green rays visible in young individuals,
becoming chestnut or dark brown in older shells. Length to 3
inches (7.6 cm).

Pseudocardinal teeth well developed, rough; two in the left
valve, one in the right. Lateral teeth straight or slightly curved,
serrated; two in the left valve, one in the right, occasionally with
a second smaller lateral tooth. Beak cavity deep. Nacre white, or
tinged with salmon, iridescent posteriorly.

Habitat Creeks to large rivers in mud, sand, or gravel.

Status Widespread and common.

Subfamily Ambleminae

47

Fusconaia flava, INHS 1 1802. Mississippi River, Buffalo County,
Wisconsin. Length: 2.4 inches (6.1 cm).

48

Mussels of the Midwest

Purple wartyback

Cyclonaias tuberculata (Rafinesque, 1820)

Other common names Missouri mapleleaf, purple pimpleback,
deerhorn.

Key characters Rounded shell with a fairly prominent wing,
beak covered with fine wavy sculpturing, no green stripe on the
umbo, purple nacre. Deep and compressed beak cavity.

Similar species Orange-foot pimpleback, pimpleback,
mapleleaf, wartyback.

Description Shell round, moderately thick, and compressed to
moderately inflated (large rivers). Anterior end rounded, poste¬
rior end somewhat squared off. Dorsal margin straight, a wing
present behind the umbo; ventral margin curved. Umbos low,
even with, or barely rising above the hinge line. Beak sculpture
of numerous wavy ridges covering the surface of the umbo. Shell
surface, except the anterior fourth, covered with tubercles,
forming small ridges on the dorsal wing. Periostracum yellowish
brown or greenish brown in young shells (rarely rayed), becom¬
ing dark brown in older shells. Length to 5 inches (12.7 cm).

Pseudocardinal teeth large and well developed; two in the
left valve, one in the right (usually with a small tooth on either
side). Lateral teeth short, striated, and straight or slightly curved;
two in the left valve, one in the right. Beak cavity very deep.
Nacre usually deep purple, occasionally white with a purple
tinge.

Habitat Medium to large rivers in gravel or mixed sand and
gravel.

Status Widespread but uncommon in most of the Midwest.
Endangered in Wisconsin. Threatened in Iowa. Species of Special
Concern in Michigan. Species of Special Interest in Ohio.

Subfamily Ambleminae

49

Cyclonaias tuberculata , INHS 4078. Tippecanoe River, Fulton County,
Indiana. Length: 3.5 inches (8.9 cm).

50

Mussels of the Midwest

Sheepnose

Plethobasus cyphyus (Rafinesque, 1820)

Other common name Bullhead.

Key characters Oblong shell with a smooth surface except for a
single row of bumps or knobs running from the umbo to the
ventral margin.

Similar species White wartyback, threehom wartyback, round
pigtoe, Wabash pigtoe, hickorynut.

Description Shell thick, oval or oblong, somewhat elongate, and
slightly inflated. Anterior end rounded, posterior end bluntly
pointed. Dorsal margin straight, ventral margin curved anteriorly,
straight posteriorly. Umbos slightly elevated above the hinge line.
Beak sculpture of two heavy ridges, visible only in young shells.
Shell smooth, except for a row of knobs or tubercles on the center
of the valve, running from the umbo to the ventral margin (some¬
times obscure). A shallow sulcus or furrow present between the
row of tubercles and the posterior ridge. Periostracum yellow or
light brown in juveniles, becoming chestnut to dark brown in
adults. Length to 5 inches (12.7 cm).

Pseudocardinal teeth rather small relative to overall shell
size; two in the left valve, one in the right (occasionally with a
smaller tubercular tooth on either side). Lateral teeth long,
straight or slightly curved; two in the left valve, one in the right.
Beak cavity shallow. Nacre white, occasionally tinged with pink
or salmon.

Habitat Medium to large rivers in gravel or mixed sand and
gravel.

Status Rare throughout its range. Endangered in Indiana, Iowa,
Ohio, and Wisconsin. Threatened in Illinois. Rare in Missouri.

Subfamily Ambleminae

51

Plethobasus cyphyus, INHS 4179. Tippecanoe River, Pulaski County,
Indiana. Length: 3.8 inches (9.7 cm).

52

Mussels of the Midwest

White wartyback

Plethobasus cicatricosus (Say, 1829)

Other common names None.

Key characters Oblong or elongate shell, light brown, with a
row of large tear-shaped tubercles running down the side of the
shell.

Similar species Sheepnose, round pigtoe, hickorynut.

Description Shell oblong, elongate, thick, and moderately
inflated. Anterior end rounded, posterior end broadly rounded.
Dorsal and ventral margins curved. Umbos low, directed forward,
and not elevated above the hinge line. Shell smooth, except for a
single row of large pustules or knobs on the center of the valve,
running from below the umbo to the edge. Periostracum yellow
or light brown in juveniles, becoming chestnut to dark brown in
adults. Faint green rays present on the umbo. Length to 5 inches
(12.7 cm).

Pseudocardinal teeth large and well developed; two in the
left valve, one in the right, with a smaller tooth on either side.
Lateral teeth rather short, straight or slightly curved; two in the
left valve, one in the right. Beak cavity relatively shallow. Nacre
white, iridescent posteriorly.

Habitat Large rivers in gravel.

Status Federally Endangered. Most likely extirpated from the
Midwest.

54

Mussels of the Midwest

Orange-foot pimpleback

Plethobasus cooperianus (Lea, 1834)

Other common name Orange-footed pearlymussel.

Key characters Round shell with pustules only on the posterior
three-fourths of the shell. No green ray on the umbo. The live
mussel has an orange foot.

Similar species Pimpleback, purple wartyback.

Description Shell thick, solid, round or slightly elongate, and
moderately inflated to compressed. Anterior end rounded,
posterior end rounded to bluntly pointed. Dorsal margin straight
or slightly curved, ventral margin curved. Umbos low, directed
forward, and only slightly elevated above the hinge line. Anterior
fourth of the shell smooth, numerous pustules present on the
posterior three-fourths. Periostracum rayless, light brown in small
shells, becoming chestnut or dark brown color in larger individu¬
als. Length to 4 inches (10.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right, with a smaller tooth on either side. Lateral teeth
rather short, straight or slightly curved; two in the left valve, one
in the right. Beak cavity very deep. Nacre white, usually with
pink or salmon near the beak cavity, iridescent posteriorly.

Habitat Large rivers in gravel or mixed sand and gravel.

Status Federally Endangered. Still extant in the Ohio River.

Subfamily Ambleminae

55

Plethobasus cooperianus, INHS 1 86. Cumberland River, Cumberland
County, Kentucky. Length: 2.5 inches (6.4 cm).

56

Mussels of the Midwest

Clubshell

Pleurobema clava (Lamarck, 1819)

Other common name Northern clubshell.

Key characters A triangular shell with an elongated posterior
end and green rays on umbo.

Similar species Pyramid pigtoe, ellipse.

Description Shell triangular, elongate, relatively thick, and
compressed to moderately inflated. Anterior end rounded,
posterior end bluntly pointed. Dorsal margin curved and slanted
down toward the point of the shell, ventral margin straight to
slightly curved. Umbos low, projected far forward and only
slightly elevated above the hinge line. Beak sculpture when
visible of a few sharp ridges at the tip of the umbo. Shell smooth,
with an occasional crease or groove present on posterior lateral
surface in some individuals. Periostracum yellowish brown with
prominent broken green rays present in the umbo region on most
specimens; older shells dark brown or black. Length to 3 inches
(7.6 cm).

Pseudocardinal teeth small and well developed; two in the
left valve, one in the right. Lateral teeth moderately long, straight
to slightly curved; two in the left valve, one in the right (occa¬
sionally with an additional shorter lateral tooth in the right valve).
Beak cavity moderately deep. Nacre pearly white, iridescent
posteriorly.

Habitat Medium to large rivers in gravel or mixed gravel and
sand.

Status Proposed for Federal Endangered status. Endangered in
Illinois, Indiana, Michigan, and Ohio.

Subfamily Ambleminae

57

Pleurobema clava, INHS 3545. Tippecanoe River, Fulton County,
Indiana. Length: 1.9 inches (4.8 cm).

58

Mussels of the Midwest

Round pigtoe

Pleurobema coccineum (Conrad, 1836)

Other common names Solid pigtoe, pink pigtoe, flat pigtoe,
bullnose.

Key characters A highly variable shell that is relatively large,
rounded or elongate, chestnut or brown, with a shallow beak
cavity.

Similar species All other pigtoes ( Fusconaia and Pleurobema ),
hickorynut, round hickorynut.

Description Shell moderately thick, round, and compressed
(medium-sized rivers) to inflated (large rivers). Anterior end
rounded, posterior end rounded to bluntly pointed. Dorsal margin
straight to slightly curved, ventral margin usually curved. Umbos
low and only slightly elevated above the hinge line. Beak
sculpture of two or three elevated ridges on the umbo. Shell
smooth. Periostracum greenish brown, light brown, or reddish
brown in juveniles, becoming chestnut or dark brown in adults,
with faint green rays visible near the beaks in some shells. Length
to 4 inches (10.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth straight. Beak cavity shallow
(medium-sized rivers) to moderately deep (large rivers). Nacre
variable from white to pink or rose-colored.

Habitat Medium to large rivers in mud, sand, or gravel.

Status Widespread but usually uncommon. May be locally
abundant in some drainages. Endangered in Iowa. Species of
Special Interest in Ohio.

Subfamily Ambleminae

59

Pleurobema coccineum , INHS 12110. Sangamon River, Champaign
County, Illinois. Length: 3.1 inches (7.9 cm).

60

Mussels of the Midwest

Rough pigtoe

Pleurobema plenum (Lea, 1840)

Other common name Pigtoe.

Key characters Shell shaped like an equilateral triangle, with a
brown, satinlike appearance and a moderately deep beak cavity.

Similar species All other pigtoes ( Fusconaia and Pleurobema).

Description Shell somewhat triangular, higher than long,
moderately thick, and inflated. Anterior and posterior ends
rounded. Dorsal and ventral margins curved. Umbos inflated and
elevated above the hinge line. Beak sculpture of two or three
elevated ridges. Shell textured, with a satin-like appearance.
Periostracum yellowish brown or light brown in small shells,
becoming dark brown in adults, with faint green rays visible near
the beaks in some shells. Length to 4 inches (10.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth straight. Beak cavity moderately
deep. Nacre usually white, occasionally pink.

Habitat Medium to large rivers in sand or gravel.

Status Federally Endangered.

Subfamily Ambleminae

61

Pleurobema plenum , INHS 13609. Barren River, Warren County,
Kentucky. Length: 3.0 inches (7.6 cm).

62

Mussels of the Midwest

Ohio pigtoe

Pleurobema cordatum (Rafinesque, 1820)

Other common name Pigtoe.

Key characters Triangular shell, umbos projecting forward,
sulcus present, deep beak cavity.

Similar species All other pigtoes ( Fusconaia and Pleurobema).

Description Shell moderately thick, triangular, and moderately
inflated. Anterior end rounded, posterior end bluntly pointed.
Dorsal margin straight, ventral margin curved anteriorly, straight
posteriorly. Umbos moderately high and projecting forward.

Beak sculpture of two or three elevated ridges. Shell smooth, a
broad shallow sulcus present in front of the posterior ridge.
Periostracum dark brown or chestnut, juveniles often lighter and
marked with green rays, particularly near the beaks. Length to 4
inches (10.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth straight to slightly curved. Beak
cavity very deep. Nacre variable, usually white, occasionally pink
or rose-colored in some individuals.

Habitat Medium to large rivers in sand or gravel in areas with
moderate flow.

Status Widespread but sporadic in the Ohio River and its
tributaries. Endangered in Ohio. Species of Special Concern in
Illinois and Indiana.

Subfamily Ambleminae

Pleurobema cordatum, INHS 780. Wabash River, White County,
Illinois. Length: 3.2 inches (8.1 cm).

64

Mussels of the Midwest

Pyramid pigtoe

Pleurobema rubrum (Rafinesque, 1820)

Other common name Pink pigtoe.

Key characters Triangular and elongate shell, shallow sulcus
present, rose-colored nacre, moderately deep beak cavity.

Similar species All other pigtoes ( Fusconaia and Pleurobema).

Description Shell thick, triangular and elongate, and moderately
inflated. Anterior end rounded, posterior end rounded to bluntly
pointed. Dorsal and ventral margins curved. Umbos high,
projected forward, and anterior to rest of shell. Shell smooth of
satin-like. Shallow sulcus present. Periostracum brown or
chestnut, with faint green rays on the umbos. Length to 4 inches
(10.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth straight or slightly curved. Beak
cavity moderately deep. Nacre pink or rose-colored in most
individuals, occasionally white.

Habitat Medium to large rivers in sand or gravel in areas with a
good current.

Status Widespread but rare in the Ohio River drainage. Federal
Candidate (Category 2). Endangered in Indiana and Ohio.

Species of Special Concern in Illinois.

Subfamily Ambleminae

65

Pleurobema rubrum , INHS 3122. Little Wabash River, Wayne County,
Illinois. Length: 2.4 inches (6.1 cm).

66

Mussels of the Midwest

Elephant-ear

Elliptio crassidens (Lamarck, 1819)

Other common names Mule’s ear, blue ham.

Key characters Heavy, solid, and triangular shell with dark
brown to black periostracum and light purple nacre.

Similar species Spike, mucket.

Description Shell thick, solid, compressed to moderately
inflated, triangular. Anterior end rounded, posterior end pointed.
Dorsal margin slightly curved, ventral margin curved in young
shells, becoming straight in older shells. Umbos low, usually not
elevated above the hinge line. Beak sculpture, if visible, of two or
three loops parallel to the growth lines, usually present only in
very small shells. Posterior ridge prominent and sharply angled.
Surface of the shell smooth. Periostracum reddish brown with
faint green rays in small shells, becoming dark brown to black in
adults. Length to 6 inches (15.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth short, roughened, and straight. Beak
cavity very shallow. Nacre color variable, usually purple,
occasionally pink or white.

Habitat Large rivers in mud, sand, or fine gravel.

Status Widespread but relatively rare in the Midwest. Locally
abundant in some parts of the Ohio and White rivers of Illinois
and Indiana. Endangered in Missouri, Ohio, and Wisconsin.
Threatened in Illinois. Species of Special Concern in Minnesota.

Subfamily Ambleminae

67

Elliptio crassidens , INHS 2655. Ohio River, Pulaski County, Illinois.
Length: 4.2 inches (10.7 cm).

68

Mussels of the Midwest

Spike

ElUptio dilatata (Rafinesque, 1820)

Other common name Lady finger.

Key characters Thick, elongate shell, short lateral teeth,
greenish brown or black, usually with a purple nacre.

Similar species Black sandshell, spectaclecase, elephant-ear,
kidneyshell.

Description Shell solid, elongate, elliptical, and compressed to
moderately inflated. Anterior end rounded, posterior end rounded
to slightly pointed. Dorsal margin straight to slightly curved,
ventral margin straight to curved in young shells, becoming
arched in older shells. Umbos low, usually not elevated above the
hinge line. Beak sculpture, if visible, of three or four heavy loops.
Surface smooth, greenish brown with faint green rays visible on
small shells, becoming dark brown to black in adults. Length to 5
inches (12.7 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth short, roughened, and straight. Beak
cavity very shallow. Nacre variable, most often purple, occasion¬
ally pink or white.

Habitat Small to large streams and occasionally lakes in mud or
gravel.

Status Widespread but sporadic in distribution. Common in
Missouri and Ohio, uncommon to rare in other states. Species of
Special Concern in Illinois.

Subfamily Ambleminae

69

Elliptio dilatata , INHS 8505. Big Kilbuck Creek, Madison County,
Indiana. Length: 4.0 inches (10.2 cm).

70

Mussels of the Midwest

Cracking pearlymussel

Hemistena lata (Rafinesque, 1820)

Other common names None.

Key characters Thin, elongate shell, yellowish brown with
broken green rays, poorly developed teeth, purple or pinkish
nacre near the beak cavity.

Similar species Fluted-shell, pondhom, yellow sandshell.

Description Shell thin, elongate, and compressed. Anterior end
rounded, posterior end pointed. Dorsal margin straight, ventral
margin straight to slightly curved. Umbos low, not elevated
above the hinge line. Beak sculpture of three or four weak ridges.
Periostracum yellowish brown or tan with broken green rays on
some shells. Length to 4 inches (10.2 cm).

Teeth poorly developed. Pseudocardinal teeth as a thickened
knob or ridge, one in each valve. Lateral teeth as a thickening of
the hinge line. Beak cavity very shallow or absent. Nacre bluish
white, with light purple or pink in the beak cavity area.

Habitat Medium to large rivers in mud, sand, or gravel.

Status Federally Endangered. Likely extirpated from the
Midwest.

Subfamily Ambleminae

71

Hemistena lata , UIMNH Z-3826. Duck River, Maury County, Tennes¬
see. Length: 2.8 inches (7.1 cm).

72

Mussels of the Midwest

Pondhorn

Uniomerus tetralasmus (Say, 1831)

Other common name Horn shell.

Key characters Relatively thin, smooth, elongate shell, light to
dark brown, pointed, and rayless. Posterior slope with a short
ridge formed by two shallow grooves on either side.

Similar species Yellow sandshell, giant floater, cracking
pearlymussel, cylindrical papershell, squawfoot.

Description Shell relatively thin, elongate, and compressed to
moderately inflated. Anterior end rounded, posterior end bluntly
or sharply pointed. Dorsal margin straight, ventral margin
straight, rarely curved. Umbos low, approximately even with the
hinge line. Beak sculpture of four or five concentric ridges. Two
shallow grooves present on the posterior slope, giving rise to a
short ridge. Surface smooth and shiny in small shells, becoming
rougher and dull in older individuals. Periostracum greenish or
yellowish brown in young individuals, adults dark brown to black
and rayless. Length to 5 inches (12.7 cm).

Pseudocardinal teeth small and thin; two in the left valve,
one in the right. Lateral teeth relatively thin, short, and straight to
slightly curved. Beak cavity shallow. Nacre white, occasionally
with a tinge of salmon.

Habitat Ponds, small creeks, and the headwaters of larger
streams in mud or sand. (This mussel can withstand periods of
desiccation and is often present in areas where few other mussels
are found.)

Status Widespread but generally uncommon. May be abundant
in its preferred habitat. Threatened in Ohio.

Subfamily Ambleminae

73

Uniomerus tetralasmus , INHS 7807. Mississippi River, Perry County,
Missouri. Length: 4.0 inches (10.2 cm).

74

Mussels of the Midwest

Paper pondshell

Utterbackia ( =Anodonta ) imbecillis (Say, 1829)

Other common names Paper floater, papershell.

Key characters Relatively small thin shell, flattened beaks,
double-looped beak sculpture, without teeth.

Similar species Cylindrical papershell, giant floater, squawfoot.

Description Shell elongate, oblong, compressed in young,
becoming inflated in older shells. Shell extremely thin, transpar¬
ent in young individuals. Anterior end rounded, posterior end
somewhat pointed. Ventral margin straight to moderately
rounded. Umbos well forward, flattened, not rising above the
hinge line. Beak sculpture double-looped, with five or six fine,
wavy ridges. Shell smooth, shiny, light yellow in young and on
the umbo of adults, rest of shell brownish green, occasionally
with fine green rays. Length to 4 inches (10.2 cm).

Both valves without teeth, hinge line straight and thin. Beak
cavities shallow or absent. Nacre white or bluish white and
iridescent posteriorly.

Habitat Ponds, lakes, and sluggish mud-bottomed pools of
creeks and rivers.

Status Widespread and locally abundant.

Subfamily Anodontinae

75

Utterbackia ( =Anodonta ) imbecillis, INHS 7203. Flat Branch, Christian
County, Illinois. Length: 2.4 inches (6.1 cm).

76

Mussels of the Midwest

Flat floater

Anodonta suborbiculata Say, 1831

Other common name Heelsplitter.

Key characters Large, thin, nearly circular shell, double-looped
beak sculpture, without teeth.

Similar species Giant floater, paper pondshell.

Description Shell large, thin, nearly circular, and compressed to
slightly inflated in some individuals. Anterior and ventral
margins broadly rounded, posterior end bluntly pointed. Dorsal
margin flattened and nearly straight. Umbos low, flattened, not
raised above the hinge line. Beak sculpture of three or four
irregular or broken double-looped ridges. A small wing occasion¬
ally present behind the umbo. Shell smooth, shiny, yellow or
yellowish green to dark brown, with fine green rays in some
individuals. Length to 7 inches (17.8 cm).

Both valves without teeth, hinge line only slightly thickened.
Beak cavity large and very shallow. Nacre white or pinkish white
and iridescent.

Habitat Ponds, lakes, or sluggish mud-bottomed pools of creeks
and rivers.

Status Locally abundant in the floodplain lakes, sloughs, and
oxbows of the Mississippi and Ohio rivers and their tributaries.
Rare in Missouri. Species of Special Interest in Ohio.

Subfamily Anodontinae

77

Anodonta suborbiculata , INHS 7854. Mississippi River, Randolph
County, Illinois. Length: 5.0 inches (12.7 cm).

78

Mussels of the Midwest

Giant floater

Pyganodon ( =Anodonta ) grandis (Say, 1 829)

Other common names Floater, stout floater, papershell,
hogshell, slopbucket.

Key characters Large, thin, elongate shell, beaks elevated
above hinge, double-looped beak sculpture, without teeth.

Similar species Flat floater, paper pondshell, squawfoot,
cylindrical papershell.

Description Shell extremely variable but usually large, some¬
what elliptical or elongate, and inflated. Shell extremely thin in
young mussels, somewhat thicker in older individuals. Anterior
end broadly rounded, posterior end bluntly pointed. Ventral
margin straight or slightly curved. Umbos full, usually located in
the anterior third of the shell but occasionally more toward the
center in the large-river form (P. grandis var. corpulenta ),
elevated above the hinge line. Beak sculpture of three to five
double-looped ridges. Shell smooth, light yellow or yellowish
green with rays visible in younger specimens, becoming dark
green to brown in older shells. Length to 10 inches (25.4 cm).

Valves without teeth, hinge line slightly thickened and
curved. Beak cavity broad and shallow. Nacre variable and may
be silvery white, cream, pink, salmon, or copper-colored.

Habitat Typically, ponds, lakes, and sluggish mud-bottomed
pools of creeks and rivers; can be found in a variety of other
habitats as well.

Status Widespread and common.

Subfamily Anodontinae

79

Pyganodon ( =Anodonta ) grandis, INHS 10319. Lone Tree Creek,
Champaign County, Illinois. Length: 5.1 inches (13.0 cm).

80

Mussels of the Midwest

Cylindrical papershell

Anodontoides ferussacianus (Lea, 1834)

Other common name Cylinder.

Key characters Thin shell, without teeth, fine V-shaped beak
sculpture.

Similar species Squawfoot, paper pondshell, giant floater.

Description Shell thin, elongate, elliptical, and inflated in
females and older males. Anterior end rounded, posterior end
bluntly pointed. Ventral margin either slightly curved, straight to
moderately arched, or pinched in the middle. Posterior ridge
rounded, prominent, and swollen in females. Umbos small, in
forward third of shell, only slightly raised above the hinge line.
Beak sculpture of three or four very fine, V-shaped ridges. Shell
smooth, shiny, yellowish green, green, or brown, lighter on the
beaks, with fine green rays, more concentrated on the posterior
half of the shell, may be absent in older shells. Length to 3 inches
(7.6 cm).

Both valves without teeth. Hinge line thin and straight to
slightly curved. Beak cavity shallow. Nacre silvery or bluish
white and iridescent posteriorly.

Habitat Small creeks and the headwaters of larger streams in
mud and sand.

Status Widespread and locally abundant. Endangered in
Missouri. Threatened in Iowa.

Subfamily Anodontinae

81

Anodontoides ferussacianus, INHS 8851. Kickapoo Creek, McLean
County, Illinois. Length: 2.5 inches (6.4 cm).

82

Mussels of the Midwest

Squawfoot

Strophitus undulatus (Say, 1817)

Other common names Strange floater, sloughfoot, creeper.

Key characters Elliptical to oval shell, thin to relatively thick,
green, dark brown, or black, with pronounced beak sculpture and
poorly developed hinge teeth. Nacre usually salmon to orange.

Similar species Cylindrical papershell, giant floater, paper
pondshell.

Description Shell elliptical, moderately compressed, and thin
when young, becoming somewhat inflated and thicker in adults.
Anterior end rounded, posterior end bluntly pointed, occasionally
truncated. Ventral margin straight to slightly curved. Umbos
slightly elevated above the hinge line and located at least one-
third from the anterior end. Beak sculpture of two or three
pronounced V-shaped ridges. Shell smooth and shiny.
Periostracum green with rays in juveniles, becoming chestnut,
dark brown, and black in older individuals. Length to 4 inches
(10.2 cm).

Pseudocardinal and lateral teeth weakly developed and
present only as thickened ridges. Hinge line curved past the
umbo. Beak cavity moderately shallow. Nacre salmon or cream-
colored, bluish white along the outer margin of the shell.

Habitat Small to medium-sized streams and occasionally large
rivers in mud, sand, or gravel.

Status Widespread and common. Threatened in Iowa.

r

Subfamily Anodontinae

83

Strophitus undulatus , INHS 1509. North Fork Vermilion River,
Vermilion County, Illinois. Length: 3.2 inches (8.1 cm).

84

Mussels of the Midwest

Elktoe

Alasmidonta marginata Say, 1818

Other common names None.

Key characters Bright yellowish green shell with numerous
dark green rays and spots; a sharply angled posterior ridge,
poorly developed teeth, and heavy beak sculpture.

Similar species Snuffbox, slippershell mussel, deertoe.

Description Shell elongate, triangular, inflated, and relatively
thin. Anterior end rounded, posterior end sharply angled, ending
in a blunt, squared point. Posterior ridge sharply angled and
prominent, posterior slope broad, flat, and covered with fine
ridges. Ventral margin straight to slightly curved. Umbos large,
located near the center of the shell, and elevated above the hinge
line. Beak sculpture of three or four heavy, double-looped ridges.
Shell smooth and dull. Periostracum yellowish green or bright
green with numerous rays and dark green spots present. Posterior
slope often lighter than rest of shell. Length to 4 inches (10.2 cm).

Pseudocardinal teeth thin and elongate; one in right, occa¬
sionally two in the left. Lateral teeth reduced to a thickened
swelling along the hinge line. Beak cavity moderately deep.
Nacre bluish white, occasionally with salmon near the beaks.

Habitat Medium-sized streams in gravel or mixed sand and
gravel.

Status Widespread but sporadic in distribution. Threatened in
Iowa.

Subfamily Anodontinae

85

Alasmidonta marginata , INHS 1 1754. Blackberry Creek, Kendall
County, Illinois. Length: 2.8 inches (7.1 cm).

86

Mussels of the Midwest

Slippershell mussel

Alasmidonta viridis (Rafinesque, 1820)

Other common names None.

Key characters Small, somewhat rectangular shell, high
posterior ridge, wavy green rays on posterior half of the shell,
poorly developed lateral teeth.

Similar species Elktoe.

Description Shell small (usually about an inch), somewhat
inflated, thin in young individuals to moderately thick in adults.
Anterior end rounded, posterior end squared or truncated.
Posterior ridge high and rounded, posterior slope flattened.
Ventral margin straight or slightly arched. Umbos full and
elevated above the hinge line. Beak sculpture of three or four
elevated ridges or loops. Shell smooth to rough and yellowish
green with numerous wavy green rays, particularly on the
posterior half of the shell. Length to 1.5 inches (3.8 cm).

Pseudocardinal teeth triangular; two in the left valve, one in
the right. Lateral teeth poorly developed, generally appearing as a
slight swelling along the hinge line. Beak cavity moderately
deep. Nacre white, iridescent on the posterior third of the shell.

Habitat Creeks and the headwaters of large rivers in sand, mud,
or fine gravel.

Status Endangered in Illinois and Iowa. Threatened in
Wisconsin.

Subfamily Anodontinae

87

Alasmidonta viridis, INHS 7866. Baker Creek, Kankakee County,
Illinois. Length: 1.4 inches (3.6 cm).

88

Mussels of the Midwest

Rock-pocketbook

Arcidens confragosus (Say, 1829)

Other common names Rockshell, grandmaw, bastard, black
pocketbook, queen.

Key characters Large, relatively thin shell, heavily sculptured,
with poorly developed lateral teeth.

Similar species Threeridge, washboard.

Description Shell thin to moderately thick, elliptical, and
inflated. Anterior end rounded, posterior end squared or bluntly
pointed. Ventral margin straight or slightly rounded. Umbos full,
elevated above the hinge line and located near the middle of the
shell. Beak sculpture of large pronounced knobs or double-
looped ridges that continue to the edge of the shell in two rows,
developing into folds on the surface. Periostracum dark green,
brown, or black. Length to 7 inches (17.8 cm).

Pseudocardinal teeth compressed, elongate; two in the left
valve, one in the right. Poorly developed lateral teeth, often
present only as a finely serrated thickening of the hinge line.
Beak cavity moderately deep. Nacre white, iridescent on the
posterior third.

Habitat Medium to large rivers in pools and areas of reduced
flow in mud and sand.

Status Extirpated from Ohio. Threatened in Wisconsin. Rare in
Missouri. Uncommon to rare in the other states of the Midwest.

Subfamily Anodontinae

89

Arcidens confragosus, INHS 9459. Mississippi River, Louisa County,
Iowa. Length: 2.8 inches (7.1 cm).

90

Mussels of the Midwest

Salamander mussel

Simpsonaias ambigua (Say, 1825)

Other common names Simpson’s shell, smooth minishell.

Key characters Small, thin, elliptical shell, poorly developed
teeth, double-looped beak sculpture, rayless.

Similar species Cylindrical papershell, spectaclecase, pondhom.

Description Shell small, thin, elongate elliptical or oval, and
compressed (male) to slightly inflated posteriorly (female).
Anterior and posterior ends rounded. Posterior ridge rounded.
Dorsal and ventral margins straight, parallel. Umbos slightly
elevated above the hinge line. Beak sculpture of three or four
double-looped bars. Shell smooth, dull, yellowish tan to dark
brown, and rayless. Length to 2 inches (5.1 cm).

Pseudocardinal teeth very small, low, rounded; one in each
valve. Lateral teeth absent. Beak cavity shallow. Nacre bluish
white, occasionally tinged with salmon near the beaks, iridescent
on the posterior half.

Habitat Medium to large rivers on mud or gravel bars and under
flat slabs or stones.

Status Federal Candidate (Category 2). Endangered in Illinois,
Michigan, and Missouri. Threatened in Wisconsin. Species of
Special Concern in Indiana. Species of Special Interest in Ohio.

Subfamily Anodontinae

91

Simpsonaias ambigua , UIMNH Z-3838. Kankakee River, Will County,
Illinois. Length: 1.8 inches (4.6 cm).

92

Mussels of the Midwest

White heeisplitter

Lasmigona complanata (Bames, 1823)

Other common names Pancake, razorback, elephant-ear,
hackle-back.

Key characters Large, rounded, compressed, relatively thin
shell, bluntly pointed at the posterior end; dark brown or black
periostracum, double-looped beak sculpture, and white nacre.

Similar species Pink heeisplitter, creek heeisplitter.

Description Shell large, rounded, and compressed, very thin in
young individuals, becoming slightly thicker in adults. Anterior
end rounded, posterior end rounded to bluntly pointed. Dorsal
margin straight with a large wing, often with several folds or
ridges that extend to the side of the shell. Ventral margin straight
to slightly curved. Umbos small, flattened, not projecting above
the hinge line. Beak sculpture of four to six distinct, double-
looped bars. Shell smooth except on the wing. Periostracum
green or greenish brown in young shells, often faintly rayed, dark
brown to black in old shells. Length to 8 inches (20.3 cm).

Pseudocardinal teeth well developed; two in the left valve,
one (occasionally two) in the right. Lateral teeth poorly devel¬
oped in both valves, represented as ridges or thickenings of the
hinge line. Beak cavity shallow to moderately deep. Nacre bluish
white or white, iridescent posteriorly.

Habitat Pools or sluggish streams with a mud, sand, or fine
gravel bottom.

Status Widespread and common.

Subfamily Anodontinae

93

Lasmigona complanata, INHS 13190. Sugar Creek, Boone County,
Indiana. Length: 3.5 inches (8.9 cm).

94

Mussels of the Midwest

Fluted-shell

Lasmigona costata (Rafinesque, 1820)

Other common names Sand mussel, squawfoot.

Key characters Elongate, compressed shell with prominent
ridges or folds (flutings) on the posterior slope and poorly
developed lateral teeth (paired in the left valve).

Similar species Creek heelsplitter.

Description Shell elongate, moderately thick, and compressed to
slightly inflated. Anterior and posterior ends sharply curved.
Dorsal and ventral margins straight. Umbos low, not projecting
above the hinge line. Beak sculpture of three or four heavy, more
or less double-looped ridges parallel with the hinge line. Promi¬
nent sculpturing on the posterior slope consisting of about 10-20
heavy, rounded ridges of folds. Additional surface sculpturing on
the lateral surface near the middle of the shell. Periostracum
green or yellowish green with numerous green rays in small
individuals, becoming chestnut or dark brown in older shells.
Length to 7 inches (17.8 cm).

Pseudocardinal teeth thick; two in the left valve, one
(occasionally two) in the right. Lateral teeth short and poorly
developed, often appearing only as ridges or thickenings of the
hinge line. Beak cavity shallow. Nacre white or bluish white and
often salmon-colored, particularly in the beak cavities.

Habitat Medium to large rivers in sand, mud, or fine gravel in
areas with slow to moderate flow.

Status Widespread but relatively uncommon. Endangered in
Iowa.

Subfamily Anodontinae

95

Lasmigona costata , INHS 1 162. Sangamon River, Champaign County,
Illinois. Length: 4.1 inches (10.4 cm).

96

Mussels of the Midwest

Creek heelsplitter

Lasmigona compressa (Lea, 1829)

Other common names None.

Key characters Relatively thin, elongate shell, well-developed
lateral teeth, prominent flattened posterior ridge, double-looped
beak sculpture.

Similar species Fluted-shell, white heelsplitter.

Description Shell small to medium-sized, elongate, relatively
thin, and compressed. Anterior end broadly rounded, posterior
end bluntly pointed and squared at the tip. Posterior ridge
prominent and broadly flattened with a small wing behind the
umbo, usually more evident in small shells. Dorsal margin
straight, ventral margin rounded, occasionally straight. Umbos
projecting slightly above the hinge line. Beak sculpture of five to
eight double-looped ridges. Shell smooth and yellowish brown
with numerous green rays in young individuals, becoming darker
green or brown in older shells. Length to 4 inches (10.2 cm).

Pseudocardinal teeth well developed; two in the left valve,
one in the right. Lateral teeth short, thin, and finely serrated; two
in the left valve, one in the right. Beak cavity very shallow. Nacre
white to salmon-colored, especially near the beak cavities.

Habitat Creeks and the headwaters of small to medium rivers in
fine gravel or sand. Rarely found in larger rivers.

Status Widespread but uncommon. Threatened in Illinois and
Iowa.

98

Mussels of the Midwest

Kidneyshell

Ptychobranchus fasciolaris (Rafinesque, 1820)

Other common names None.

Key characters Thick, kidney-shaped shell, heavy teeth,
yellowish brown, with broken green rays.

Similar species Spike, mucket, ellipse, rainbow.

Description Shell solid, thick, elongate, compressed, and
kidney-shaped. Anterior end rounded, posterior end bluntly
pointed. Dorsal margin straight to slightly curved, ventral margin
curved, straight, or arched. Umbos low, approximately even with
the hinge line. Beak sculpture, if visible, of two or three indistinct
ridges. Shell smooth. Periostracum yellowish brown to brown
with broad green rays, usually interrupted or broken. Length to 6
inches (15.2 cm).

Pseudocardinal teeth thick and triangular; two in the left
valve, one in the right, sometimes with a low, roughened tubercu¬
lar tooth on either side. Lateral teeth short, nearly straight, heavy,
and serrated. Beak cavity shallow or absent. Some females with a
fold or groove on the inside. Nacre pearly white.

Habitat Medium to large rivers in gravel.

Status Fairly widespread but only locally abundant. Disappear¬
ing from parts of its range. Endangered in Illinois.

Subfamily Lampsilinae

99

Ptychobranchus fasciolaris, INHS 3475. Tippecanoe River, Fulton
County, Indiana. Length: 4.5 inches (1 1 .4 cm).

100

Mussels of the Midwest

Threehorn wartyback

Obliquaria reflexa Rafinesque, 1820

Other common names Homyback, three dot, three knot.

Key characters The large knobs that alternate from side to side
will distinguish this mussel from all other species found in the
Midwest.

Similar species Pimpleback, sheepnose, tubercled blossom.

Description Shell usually small, rounded, moderately thick, and
inflated. Anterior end rounded, posterior end bluntly pointed. A
row of three or four large, elevated knobs extending from the
beak to the center of the ventral margin, with the knobs alternat¬
ing in position with those of the other side. Often a broad
depression present between the knobs. Beaks elevated and curved
inward. Periostracum highly variable in color from light yellow¬
ish brown to green and dark brown. Shell usually covered with
numerous fine, dark green, broken rays. Length to 3 inches
(7.6 cm).

Pseudocardinal teeth heavy and serrated; two in the left
valve, one in the right. Lateral teeth straight to slightly curved,
short, and serrated. Beak cavity shallow to moderately deep.
Nacre pearly white.

Habitat Large rivers in sand or gravel; may be locally abundant
in impoundments.

Status Widespread and common in the large rivers of the
Midwest. Threatened in Ohio.

Subfamily Lampsilinae

101

Obliquaria reflexa, INHS 3052. Rock River, Rock Island County,
Illinois. Length: 2.2 inches (5.6 cm).

102

Mussels of the Midwest

Fanshell

Cyprogenia stegaria (Rafinesque, 1820)

Other common names Eastern fanshell, Ohio fanshell,
pimpleback, ringed wartyback.

Key characters Rounded shape, numerous pustules, elevated
growth lines, broken green rays.

Similar species Pimpleback, purple pimpleback.

Description Shell rounded, solid, and moderately inflated.
Anterior margin rounded, posterior margin bluntly rounded or
truncated. Ventral margin broadly rounded. Umbos not elevated
above the hinge line. Beak sculpture, if visible, of a few weak
ridges. Growth lines appear as distinct elevated ridges. Numerous
pustules usually concentrated in the center but occasionally
covering the entire surface of the shell. Periostracum usually
greenish yellow, with a pattern of dark green rays made up of
numerous smaller broken lines or dots. Length to 3 inches
(7.6 cm).

Pseudocardinal teeth relatively large and serrated; two in the
left valve, one in the right. Lateral teeth roughened, straight to
slightly curved, heavy and very short. Interdentum wide. Beak
cavity shallow to moderately deep. Nacre white, iridescent
posteriorly.

Habitat Medium to large rivers in gravel riffles.

Status Federally Endangered.

Subfamily Lampsilinae

103

Cyprogenia stegaria, UIMNH Z- 14954. Wabash River, Posey County,
Indiana. Length: 1.9 inches (4.8 cm).

104

Mussels of the Midwest

Mucket

Actinonaias ligamentina (Lamarck, 1819)

Other common names Grass mucket, brass mucket, steamboat
mucket.

Key characters Relatively large, oblong, thick shell, yellowish
brown, with green rays and a relatively shallow beak cavity.

Similar species Plain pocketbook, fatmucket, Higgins eye, pink
mucket, elephant-ear, ellipse, hickorynut.

Description Shell large, elliptical or oblong, thick, usually
heavy, and compressed to moderately inflated. Anterior end
rounded, posterior end bluntly pointed. Umbos slightly elevated
above the hinge line. Beak sculpture of a few fine, double-looped
ridges, usually visible only in young shells. Periostracum smooth,
yellowish brown, with numerous green rays. Large shells dark
brown with faint green rays or rayless. Length to 7 inches
(17.8 cm).

Pseudocardinal teeth large, slightly elevated and serrated;
two in the left valve, one in the right. Lateral teeth straight to
slightly curved, thin, and moderately long. Beak cavity shallow to
moderately deep. Nacre white, occasionally tinged with pink or
salmon, iridescent posteriorly.

Habitat Medium to large rivers in gravel or mixed sand and
gravel.

Status Widespread and locally abundant. Extirpated from Ohio.

Subfamily Lampsilinae

Actinonaias ligamentina , INHS 13303. Iroquois River, Kankakee
County, Illinois. Length: 3.6 inches (9.1 cm).

106

Mussels of the Midwest

Butterfly

Ellipsaria lineolata (Rafinesque, 1820)

Other common names None.

Key characters Triangular, flattened shell, sharply angled
posterior ridge, yellowish brown, with broken brown rays.

Similar species Deertoe.

Description Shell somewhat triangular, thick, solid, and
compressed. Anterior end broadly rounded, posterior end pointed.
Umbos compressed, directed forward, and not elevated above the
hinge line. Posterior ridge sharply defined. Lateral surfaces
broadly flattened, less so in older females. Beak sculpture, if
visible, of a few fine, double-looped ridges. Shell smooth, yellow
or yellowish green, with scattered brown rays that are usually
broken into V-shaped or irregular rectangular blotches. Old shells
with faint brown rays or rayless. Length to 4 inches (10.2 cm).

Pseudocardinal teeth relatively large, slightly elevated,
serrated, and divergent; two in the left valve, one in the right.
Usually two lateral teeth in each valve, serrated, short, and
straight. Interdentum wide. Beak cavity shallow to moderately
deep. Nacre white, iridescent posteriorly.

Habitat Large rivers in sand or gravel.

Status Widespread but only locally abundant. Disappearing
from many areas where it formerly occurred. Endangered in Ohio
and Wisconsin. Threatened in Iowa. Species of Special Concern
in Illinois.

Subfamily Lampsilinae

107

Ellipsaria lineolata , INHS 3046. Rock River, Rock Island County,
Illinois. Length: 2.5 inches (6.4 cm).

108

Mussels of the Midwest

Hickorynut

Obovaria olivaria (Rafinesque, 1820)

Other common names Eggshell, chestnut shell, glassyback.

Key characters A thick, rounded or oblong shell with a smooth
surface, greenish or yellowish brown, shallow beak cavity.

Similar species Round hickorynut, round pigtoe, ring pink,
ebonyshell, Higgins eye, mucket.

Description Shell oval or oblong, thick, solid, and inflated.
Anterior and posterior ends broadly rounded. Umbos slightly
elevated above the hinge line, rounded, curved inward, and
directed forward. Beak sculpture of four or five delicate, double-
looped bars, usually evident only in very small shells. Shell
smooth, olive green or yellowish brown, faintly rayed in young
shells, becoming dark brown in old individuals. Length to 4
inches (10.2 cm).

Pseudocardinal teeth triangular, relatively small, widely
divergent, and horizontal. Lateral teeth straight to slightly curved,
wide, heavy, and fairly long. Interdentum narrow. Beak cavity
shallow. Nacre white, iridescent posteriorly.

Habitat Large rivers (rarely in medium or small streams) in sand
or mixed sand and gravel.

Status Widespread and common in the Wabash and lower Ohio
rivers but disappearing in the Mississippi and upper Ohio rivers.
Endangered in Ohio. Species of Special Concern in Michigan.
Watch List in Missouri.

Subfami ly Lamps i li nae

109

Obovaria olivaria, INHS 6124. Wabash River, Fountain County,
Indiana. Length: 3.0 inches (7.6 cm).

110

Mussels of the Midwest

Round hickorynut

Obovaria subrotunda (Rafinesque, 1820)

Other common names None.

Key characters Almost perfectly round, relatively small shell,
with a smooth, brown, ray less periostracum.

Similar species Hickorynut, round pigtoe, ebonyshell.

Description Shell round or circular, moderately thick, and
inflated. Anterior and posterior ends rounded in males, somewhat
truncated in females. Umbos low and centrally placed, slightly
elevated above the hinge line. Beak sculpture of a few indistinct,
concentric ridges, usually evident only on very young shells.

Shell smooth, growth lines dark but often indistinct. Periostracum
yellowish brown to dark chestnut brown or blackish, and rayless.
Length to 3 inches (7.6 cm).

Pseudocardinal teeth moderately small, serrated, and
divergent. Lateral teeth slightly curved, fairly short, and moder¬
ately thin. Interdentum narrow or absent. Beak cavity fairly deep.
Nacre white, iridescent posteriorly.

Habitat Medium-sized streams in sand and gravel in areas with
moderate flow.

Status Sporadic in distribution, disappearing from many areas.
Endangered in Illinois and Michigan.

Subfamily Lampsilinae

111

Obovaha subrotunda , INHS 4083. Tippecanoe River, Fulton County,
Indiana. Length: 2.1 inches (5.3 cm).

112

Mussels of the Midwest

Ring pink

Obovaria retusa (Lamarck, 1819)

Other common name Golf stick.

Key characters Thick shell, recurved umbos, brown
periostracum, nacre purple inside the pallial line.

Similar species Ebonyshell, round pigtoe, round hickorynut,
hickorynut.

Description Shell thick, solid, and somewhat inflated, with an
unusual dorso-ventrally elongated recurved shape. Anterior,
ventral, and posterior margins rounded. Umbos high, full,
swollen, and directed forward. Shell surface smooth or clothlike.
The female has a distinct groove on the posterior ridge.
Periostracum reddish brown, occasionally dark brown or black¬
ish. Length to 3 inches (7.6 cm).

Pseudocardinal teeth large, elevated, heavy, and serrated;
two in the left valve, one large one in the right, often with a
smaller tooth on either side. Lateral teeth short, straight to
slightly curved, and serrated. Interdentum moderately wide. Beak
cavity deep. Nacre pink or purple within the pallial line, white
around the margins.

Habitat Large rivers in gravel or sand.

Status Lederally Endangered. Extirpated from the Midwest.

Subfamily Lampsilinae

113

Obovaria retusa , UIMNH Z- 14979. Wabash River, Posey County,
Indiana. Length: 2.0 inches (5.1 cm).

114

Mussels of the Midwest

Deertoe

Truncilla truncata Rafinesque, 1820

Other common name Deerhom.

Key characters Triangular shell, sharply angled posterior ridge,
inflated, yellow, green, or brown, usually with numerous green
rays.

Similar species Fawnsfoot, butterfly, Wabash pigtoe, elktoe.

Description Shell triangular, thin to moderately thick, and
somewhat inflated. Anterior end rounded, posterior end bluntly
pointed or truncated. Posterior ridge sharply angled. Umbos full
and elevated well above the hinge line. Beak sculpture of three to
five fine, double-looped ridges. Periostracum highly variable in
color from yellow, green, yellowish brown to dark brown, with
numerous green rays of variable widths and shape, often com¬
posed of fine broken lines or V-shaped or zigzag markings;
occasionally rayless. Length to 2 inches (5.1 cm).

Pseudocardinal teeth well developed, elevated and divergent;
two in the left valve, one in the right. Lateral teeth straight to
slightly curved, high, roughened, occasionally with an incom¬
plete, smaller inner lateral developed. Interdentum narrow or
absent. Beak cavity shallow to moderately deep. Nacre white,
occasionally pink, iridescent posteriorly.

Habitat Medium to large rivers in mud, sand, or gravel.

Status Widespread and common throughout much of its range.
Species of Special Interest in Ohio.

Subfamily Lampsilinae

115

Truncilla truncata, INHS 4568. Sangamon River, Piatt County, Illinois.
Length: 2.0 inches (5.1 cm).

116

Mussels of the Midwest

Fawnsfoot

Truncilla donaciformis (Lea, 1828)

Other common name Little pocketbook.

Key characters Small, elongate shell, greenish yellow, with
zigzag markings.

Similar species Deertoe, rayed bean.

Description Shell small, elongate, somewhat oblong, relatively
thin, and compressed to moderately inflated. Anterior end
rounded, posterior end pointed, ventral margin smoothly rounded.
Umbos full, centrally located, and slightly elevated above the
hinge line. Beak sculpture of five or six double-looped bars.
Periostracum variable from yellow to greenish brown, with
numerous dark green rays made up of many smaller broken, Y-¬
shaped or zigzag lines. Length to 2 inches (5.1 cm).

Pseudocardinal teeth small, roughened, and elevated; two in
the left valve, one in the right. Lateral teeth thin, relatively long,
and straight to slightly curved. Beak cavity moderately shallow.
Nacre white, iridescent posteriorly.

Habitat Large rivers or the lower reaches of medium-sized
streams in sand or gravel.

Status Widespread and common throughout most of its range.
Threatened in Ohio.

Subfamily Lampsilinae

117

Truncilla donaciformis, INHS 3060. Rock River, Rock Island County,
Illinois. Length: 1.6 inches (4.1 cm).

118

Mussels of the Midwest

Scaleshell

Leptodea leptodon (Rafinesque, 1820)

Other common name Narrow papershell.

Key characters A thin, elongate, compressed shell, yellowish
green or brown, with fine green rays, pointed posterior end,
poorly developed pseudocardinal teeth, and very fine lateral
teeth.

Similar species Fragile papershell.

Description Shell relatively small, elongate, thin, and com¬
pressed. Anterior end rounded, posterior end pointed. Dorsal
margin straight, ventral margin straight to broadly curved. Umbos
small and low, about even with the hinge line. Beak sculpture, if
visible, of four or five double-looped ridges. Shell smooth,
yellowish green or brown, with numerous faint green rays.

Length to 4 inches (10.2 cm).

Pseudocardinal teeth reduced to a small thickened ridge.
Lateral teeth moderately long; two low, indistinct lateral teeth in
left valve, one fine tooth in the right. Beak cavity very shallow or
absent. Nacre pinkish white or light purple and highly iridescent.

Habitat Large rivers in mud.

Status Federal Candidate (Category 2). Extirpated from Ohio.
Likely extirpated from Illinois, Iowa, and Indiana. Rare in
Missouri. Species of Special Concern in Michigan.

Subfamily Lampsilinae

119

Leptodea leptodon, UIMNH Z- 14296. Wabash River, Vigo County,
Indiana. Length: 3.5 inches (8.9 cm).

120

Mussels of the Midwest

Fragile papershell

Leptodea fragilis (Rafinesque, 1820)

Other common names Papershell, cottonmouth.

Key characters Thin, fragile, elongate shell, yellow or yellow¬
ish green with faint green rays, rounded posterior end, pinkish
white and iridescent nacre.

Similar species Scaleshell, pink papershell.

Description Shell somewhat oblong, thin, and compressed.
Anterior end rounded, posterior end rounded in males and
broadly expanded in females. Dorsal wing present in young
shells, becoming greatly reduced or absent in older individuals.
Umbos flattened and only slightly elevated above the hinge line.
Beak sculpture of three or four faint, double-looped bars. Shell
smooth, shiny to dull, yellow or yellowish green, usually with
numerous light green, indistinct rays; some rayless. Length to 6
inches (15.2 cm).

Pseudocardinal teeth small, reduced to a thin ridge in small
shells, becoming a thickened swelling in older shells; two in the
left valve, one in the right. Lateral teeth long, thin, and com¬
pressed; two in the left valve, one in the right. Beak cavity
shallow or absent. Nacre pinkish white or pink and highly
iridescent.

Habitat Streams of all sizes in mud, sand, or gravel.

Status Widespread and common.

Subfamily Lampsilinae

121

Leptodea fragilis, INHS 8019. Henderson Creek, Henderson County,
Illinois. Length: 4.8 inches (12.2 cm).

122

Mussels of the Midwest

Pink papershell

Potamilus ohiensis (Rafinesque, 1820)

Other common names Papershell, fragile heelsplitter.

Key characters Thin, shiny, elongate and compressed shell, tan
or olive green to dark brown, with pink to purple nacre.

Similar species Fragile papershell, pink heelsplitter.

Description Shell elongate, thin, fragile, and compressed.
Anterior and posterior ends rounded. A large wing present behind
the umbo, with a smaller wing in front, but often missing in older
shells. Umbos flattened and not elevated above the hinge line.
Beak sculpture of three or four small, thickened ridges. Shell very
shiny, rayless, tan or olive green to dark brown (dark brown
particularly in older shells). Length to 7 inches (17.8 cm).

Pseudocardinal teeth thin, elongate, and slightly roughened;
one in the left valve, two in the right. Lateral teeth long, thin,
elevated, and straight or slightly curved. Beak cavity shallow.
Nacre typically light purple, occasionally pink, and highly
iridescent.

Habitat Medium to large rivers in silt, mud, or sand.

Status Widespread and locally common.

Subfamily Lampsilinae

123

Potamilus ohiensis, INHS 2197. Kankakee River, Will County, Illinois.
Length: 4.0 inches (10.2 cm).

124

Mussels of the Midwest

Pink heelsplitter

Potamilus alatus (Say, 1817)

Other common names Purple heelsplitter, pancake, hatchet-
back.

Key characters An elongate and rectangular shell, well-
developed posterior wing, dark green to dark brown, with a
purple or pink nacre.

Similar species Bleufer, white heelsplitter, pink papershell.

Description Shell large, elongate, laterally compressed and
somewhat rectangular, thin in young shells to moderately thick in
older individuals. Anterior end rounded, posterior end bluntly
squared or truncated. Umbos flattened and only slightly elevated
above the hinge line. Beak sculpture of three or four concentric
ridges, visible only in small shells. Large wing present posterior
to the umbos. Shell smooth, dark green or brown, becoming black
in old individuals. Young shells typically marked with dark green
rays that become fainter with age. Length to 8 inches (20.3 cm).

Pseudocardinal teeth small, roughened, thin and divergent;
two in the left valve, two in the right. Lateral teeth long, thin, and
straight to slightly curved. Beak cavity shallow. Nacre usually
purple or pinkish purple, rarely white; highly iridescent.

Habitat Medium to large rivers in mud or mixed mud, sand, and
gravel.

Status Widespread and relatively common.

Subfamily Lampsilinae

125

Potamilus alatus, INHS 8049. Mackinaw River, McLean County,
Illinois. Length: 3.8 inches (9.7 cm).

126

Mussels of the Midwest

Bleufer

Potamilus purpuratus (Lamarck, 1819)

Other common names Blooper, blue mucket, blue hen, purple
pocketbook.

Key characters An elongate and rectangular shell, inflated, dark
green to black, with a purple or pink nacre.

Similar species Pink heelsplitter.

Description Shell rectangular, moderately to greatly inflated,
thin in young to moderately thick in older individuals. Anterior
end rounded, posterior end bluntly squared or truncated. Umbos
flattened, only slightly elevated above the hinge line. A low wing
may be present behind the umbo. Beak sculpture of three or four
double-looped ridges, visible only in young shells. Shell smooth,
brown, becoming black in old individuals. Young mussels
typically marked with dark green rays that become fainter with
age. Length to 8 inches (20.3 cm).

Pseudocardinal teeth small, roughened and divergent; two in
the left valve, two in the right. Lateral teeth long, thin, and
curved. Beak cavity shallow. Nacre deep purple and highly
iridescent.

Habitat Large rivers in mud or mixed mud and gravel.

Status A southern species rarely found above the confluence of
the Mississippi and Ohio rivers. Species of Special Concern in
Illinois.

Subfamily Lampsilinae

Potamilus purpuratus, INHS 12852. Mississippi River, Fulton County,
Kentucky. Length: 4.1 inches (10.4 cm).

128

Mussels of the Midwest

Fat pocketbook

Potamilus capax (Green, 1832)

Other common names Pocketbook, grandmaw.

Key characters A rounded, greatly inflated shell, thin to
moderately thick, S-shaped hinge line, tan or light brown, rayless,
and shiny.

Similar species Plain pocketbook, pocketbook.

Description Shell round to somewhat oblong, greatly inflated,
and thin (young) to moderately thick (adults). Anterior and
posterior ends rounded. Umbos greatly inflated, elevated, and
turned inward. Beak sculpture of a few faint ridges, visible only
in young shells. Small posterior wing present in young mussels.
Surface usually smooth and very shiny. Periostracum rayless,
yellow, yellowish tan, or olive, becoming dark brown in older
individuals. Length to 5 inches (12.7 cm).

Pseudocardinal teeth thin, compressed, and elevated; two in
each valve. Lateral teeth thin and greatly curved; two in the left
valve, one in the right. Hinge line S-shaped. Beak cavity very
deep. Nacre white, sometimes tinged with pink or salmon.

Habitat Large rivers in slow-flowing water in mud or sand.

Status Federally Endangered.

Subfamily Lampsilinae

129

Potamilus capax, INHS 8290. Wabash River, Posey County, Indiana.
Length: 4.5 inches (1 1.4 cm).

130

Mussels of the Midwest

Lilliput

Toxolasma parvus (Bames, 1823)

Other common names None.

Key characters Small shell, usually no more than an inch long,
elliptical or cylindrical, dark green or brown, with a clothlike
texture.

Similar species Purple lilliput, Texas lilliput, little

spectaclecase.

Description Shell small, elliptical or cylindrical, relatively solid,
and inflated. Anterior and posterior ends rounded. Umbos
inflated and slightly elevated above the hinge line. Beak sculpture
consists of five or six distinct angled ridges. Surface of the shell
with a clothlike texture, dark green, brown, or dark brown and
rayless. Length to 1.5 inches (3.8 cm).

Pseudocardinal teeth thin, elevated, compressed, and
serrated; two in the left valve, one or two in the right. Lateral
teeth long, thin and straight; two in the left valve, one in the right.
Beak cavity moderately deep. Nacre silvery or bluish white and
highly iridescent.

Habitat Ponds, lakes, and creeks to large rivers in mud, sand, or
fine gravel.

Status Widespread and locally abundant.

Subfamily Lampsilinae

131

Toxolasma parvus, INHS 10134. Otter Creek, LaSalle County, Illinois.
Length: 1.2 inches (3.0 cm).

132

Mussels of the Midwest

Purple lilliput

Toxolasma lividus (Rafinesque, 1831)

Other common name Little purple.

Key characters A small, slightly elongate shell, dark brown,
pointed or truncated on the posterior end, with a purple nacre.

Similar species Lilliput, Texas lilliput, little spectaclecase.

Description Shell small, rounded to somewhat oblong, rela¬
tively solid, and inflated. Anterior end rounded, posterior end
bluntly pointed (males) or truncated (females). Umbos inflated
and slightly elevated above the hinge line. Beak sculpture of
three or four heavy bars. Periostracum tan or dark green to dark
brown, becoming black in older shells. Length to 1 inch
(2.5 cm).

Pseudocardinal teeth well developed, elevated and serrated;
two in the left valve, one in the right. Lateral teeth straight to
slightly curved; two in the left valve, one in the right. Beak cavity
variable from very shallow to moderately deep. Nacre purple,
usually lighter near the ventral margin, and iridescent.

Habitat Lakes and small to medium streams in gravel.

Status Federal Candidate (Category 2). Endangered in Illinois,
Michigan, and Ohio. Watch List in Missouri.

i

Subfamily Lampsilinae

133

Toxolasma lividus, UIMNH Z- 14295. Tippecanoe Lake, Kosciusko
County, Indiana. Length: 1.2 inches (3.0 cm) for both male (top) and
female (bottom).

134

Mussels of the Midwest

Texas lilliput

Toxolasma texasensis (Lea, 1857)

Other common names None.

Key characters Small shell, pointed or truncated on the poste¬
rior end, and greenish brown or black with a clothlike texture.

Similar species Lilliput, purple lilliput, little spectaclecase,
pondmussel.

Description Shell elongate, thin to relatively solid, and moder¬
ately inflated. Anterior end rounded, posterior end pointed
(males) or truncated (females). Umbos even with or only slightly
elevated above the hinge line. Beak sculpture of five or six strong
angular ridges. Periostracum greenish brown to black with
clothlike texture. Length to 2.5 inches (6.4 cm).

Pseudocardinal teeth relatively thin and compressed,
elevated and serrated; two in the left valve, one in the right.
Lateral teeth long, straight or curved; two in the left valve, one in
the right. Beak cavity shallow. Nacre white, occasionally tinged
with salmon in the beak cavity and center of the shell.

Habitat Small to medium streams or sloughs in mud or sand in
slow-flowing water.

Status Essentially a southern species that is rare in the Midwest.

Subfamily Lampsilinae

135

Toxolasma texasensis, UIMNH Z- 151 15. Wabash River, White County,
Illinois. Length: 2.2 inches (5.6 cm) for male (top), 1.8 inches (4.6 cm)
for female (bottom).

136

Mussels of the Midwest

Black sandshell

Ligumia recta (Lamarck, 1819)

Other common names Black sand mussel, long John, honest
John, sow’s ear, lady’s slipper.

Key characters Elongate shell, pointed on the posterior end,
smooth surface, usually dark brown to black, with a pinkish or
purple nacre.

Similar species Spike, spectaclecase, yellow sandshell.

Description Shell elongate, solid, and moderately compressed.
Anterior end rounded, posterior end pointed in males, saber¬
shaped in females. Dorsal margin straight, ventral margin straight
to curved. Umbos low, only slightly elevated above the hinge
line. Beak sculpture, if visible, of two or three indistinct, double-
looped bars. Shell smooth and shiny, dark green, brown, or black,
with green rays visible on some individuals. Length to 8 inches
(20.3 cm).

Pseudocardinal teeth triangular, serrated, and divergent; two
in the left valve, one in the right, occasionally with a small tooth
anteriorly. Lateral teeth long, moderately thin, and straight. Beak
cavity shallow. Nacre variable from white, pink, and salmon to
deep purple, iridescent posteriorly.

Habitat Medium to large rivers in riffles or raceways in gravel
or firm sand.

Status Widely distributed but uncommon in much of the
Midwest. Threatened in Ohio.

Subfamily Lampsilinae

137

Ligumia recta , INHS 1 1769 and 11722. Mississippi River, Rock Island
County, Illinois. Length: 4.6 inches (1 1.7 cm) for male (top), 4.8 inches
(12.2 cm) for female (bottom).

138

Mussels of the Midwest

Pondmussel

Ligumia subrostrata (Say, 1831)

Other common names Western pondmussel, common
pondmussel, western sand shell.

Key characters Small, elongate shell, pointed or truncated on
the posterior end, with thin teeth, beak with numerous wavy
ridges if not entirely eroded, yellowish brown with green rays.

Similar species Black sandshell, little spectaclecase, Texas
lilliput, pondhom.

Description Shell relatively small, thin, elongate, and com¬
pressed. Anterior end rounded, posterior end pointed in males,
saber-shaped in females. Dorsal and ventral margins straight.
Umbos slightly elevated above the hinge line. Beak sculpture of
six to eight distinct, wavy ridges but often eroded and not visible.
Shell smooth, dull, greenish yellow, becoming darker brown to
black in older shells. Dark green rays present but faint in some
specimens. Length to 3 inches (7.6 cm).

Pseudocardinal teeth thin, compressed, and divergent; two in
the left valve, one in the right. Lateral teeth long, thin, and
straight; two in the left valve, one in the right. Beak cavity
relatively shallow. Nacre white and highly iridescent posteriorly.

Habitat Small creeks or ponds in mud or sand.

Status May be common in its preferred habitat. Extirpated from
Ohio.

Subfamily Lampsilinae

139

Ligumia subrostrata, INHS 5569. Skillet Fork, Marion County, Illinois.
Length: 2.9 inches (7.4 cm) for male (top), 2.5 inches (6.4 cm) for
female (bottom).

140

Mussels of the Midwest

Ellipse

V enustaconcha ellipsiformis (Conrad, 1836)

Other common names None.

Key characters Small, elongate shell, relatively thick for its
size, with short, heavy lateral teeth and numerous wavy green
rays on the posterior half of the shell.

Similar species Rayed bean, rainbow, mucket, spike.

Description Shell small, solid, elliptical, and compressed.
Anterior end rounded, posterior end bluntly pointed. Ventral
margin straight to slightly curved. Umbos only slightly elevated
above the hinge line. Beak sculpture of three or four very fine,
double-looped ridges. Shell usually smooth, with a few wrinkles
or folds on the posterior half in older shells. Periostracum green
or greenish yellow with numerous dark green rays, becoming
wavy on the posterior half of the shell. Length to 3 inches
(7.6 cm).

Pseudocardinal teeth triangular, heavy, roughened, and
divergent; two in the left valve, one in the right (occasionally
with a thin, ridgelike tooth in front). Lateral teeth relatively short,
thick, and straight to slightly curved. Beak cavity shallow. Nacre
white, iridescent posteriorly.

Habitat Small to medium streams in gravel or mixed sand and
gravel.

Status Uncommon. Extirpated from Ohio. Threatened in Iowa
and Wisconsin. Species of Special Concern in Illinois and
Indiana.

Subfamily Lampsilinae

141

Venustaconcha ellipsiformis, INHS 4137. Rock River, Illinois. Length:
2.9 inches (7.4 cm).

142

Mussels of the Midwest

Rayed bean

Villosa fabalis (Lea, 1831)

Other common name Bean shell.

Key characters Very small and solid shell with numerous wavy
green lines on the outer surface and teeth that are unusually
heavy and thick for their size.

Similar species Ellipse, rainbow.

Description Shell small (usually under 1 inch [2.5 cm]),
elongate, thick, solid, and moderately inflated. Anterior end
rounded, posterior end rounded to bluntly pointed. Dorsal margin
straight, ventral margin straight to slightly curved. Umbos
slightly elevated above the hinge line. Beak sculpture, if visible,
of two or three heavy ridges. Periostracum green, yellowish
green, or brown with numerous wavy green rays. Length to 1.5
inches (3.8 cm).

Pseudocardinal teeth triangular, relatively heavy and large;
two in the left valve, one in the right. Lateral teeth short, heavy;
two in the left valve, one in the right. Beak cavity shallow. Nacre
white or bluish white, iridescent posteriorly.

Habitat Lakes and small to large streams in sand or gravel.

Status Lederal Candidate (Category 2). Endangered in Illinois,
Michigan, and Ohio. Species of Special Concern in Indiana.

Subfamily Lampsilinae

143

Villosa fabalis, INHS 4885. Salt Fork Vermilion River, Champaign
County, Illinois. Length: 1.1 inches (2.8 cm) for male (top), 1.0 inch (2.5
cm) for female (bottom).

144

Mussels of the Midwest

Rainbow

Villosa iris (Lea, 1829)

Other common name Rainbow shell.

Key characters Small, relatively thin, and elongate shell,
distinct double-looped beak sculpture, yellow, with numerous
broken green rays.

Similar species Ellipse, rayed bean, fatmucket, mucket.

Description Shell small, elongate, relatively thin, and com¬
pressed (males) to moderately inflated (females). Anterior end
rounded, posterior end rounded (females) to bluntly pointed
(males). Umbos even with or slightly elevated above hinge line.
Beak sculpture of four to six distinct, double-looped bars.
Periostracum yellow or greenish yellow, with dark green rays,
often interrupted. Length to 3 inches (7.6 cm).

Pseudocardinal teeth small, triangular, and somewhat
divergent; two in the left valve, one in the right. Lateral teeth
long, thin, and straight to slightly curved. Beak cavity shallow.
Nacre silvery white and highly iridescent on the posterior half,
giving this species its common name.

Habitat Small to medium streams in coarse sand or gravel.

Status Widespread but disappearing from the western part of its
range. Endangered in Illinois and Wisconsin.

Subfamily Lampsilinae

145

Villosa iris , UIMNH Z- 14080. Tippecanoe River, White County,
Indiana. Length: 2.0 inches (5.1 cm) for male (top), 1.9 inches (4.8 cm)
for female (bottom).

146

Mussels of the Midwest

Little spectaclecase

Villosa lienosa (Conrad, 1834)

Other common name Black creek shell.

Key characters Small shell, dark brown with green rays (often
obscure), somewhat elongate, with distinct double-looped beak
sculpture and pointed or truncated posterior end.

Similar species Pondmussel, pondhom, Texas lilliput.

Description Shell small, slightly elongate, thin to moderately
thick, compressed in males and inflated in females. Anterior end
rounded, posterior end bluntly pointed (males) or truncated
(females). Dorsal margin straight, ventral margin straight to
slightly curved. Umbos elevated above the hinge line. Beak
sculpture of four to seven distinct, double-looped bars. Perio-
stracum green to dark brown, with green rays (often obscure).
Length to 2.5 inches (6.4 cm).

Pseudocardinal teeth relatively small and compressed; two in
the left valve, one in the right, with a smaller tooth present
anteriorly in some shells. Lateral teeth elongate, thin, and
straight. Nacre white or bluish white, occasionally tinged with
salmon, iridescent posteriorly.

Habitat Small to medium streams in sand or gravel.

Status Widespread but uncommon in the Ohio River drainage.
Endangered in Illinois and Ohio. Species of Special Concern in
Indiana.

Subfamily Lampsilinae

147

Villosa lienosa , INHS 4844. North Fork Vermilion River, Vermilion
County, Illinois. Length: 1.8 inches (4.6 cm) for both male (top) and
female (bottom).

148

Mussels of the Midwest

Yellow sandshell

Lampsilis teres (Rafinesque, 1820)

Other common names Banana shell, bank climber, slough
sandshell, creeper, sand clam, luster shell.

Key characters Elongate, relatively thick, often glossy shell;
adults usually solid yellow, juveniles yellowish green with fine
green rays.

Similar species Fat mucket, black sandshell, pondhom,
scaleshell.

Description Shell relatively large, elongate, moderately thick,
and somewhat inflated. Anterior end rounded, posterior end
pointed in males, truncated in females. Dorsal margin straight,
ventral margin straight or occasionally pinched in the middle.
Umbos only slightly elevated above the hinge line. Beak sculp¬
ture of four to six double-looped ridges. Shell smooth, very shiny
when young, becoming dull with age. Periostracum yellow,
usually with green rays in young shells, rayless in older individu¬
als. Length to 6 inches (15.2 cm).

Pseudocardinal teeth elongate and compressed; two in the
left valve, one in the right (occasionally with a thin, ridgelike
tooth in front). Lateral teeth long and straight to slightly curved;
two in the left valve, one in the right. Beak cavity moderately
deep. Nacre silvery white, occasionally tinged with cream or
salmon near the beak cavity, iridescent posteriorly.

Habitat Medium to large rivers in sand or fine gravel.

Status Endangered in Iowa, Ohio, and Wisconsin.

Subfamily Lampsilinae

149

Lampsilis teres, INHS 7386. Embarras River, Lawrence County, Illinois.
Length: 4.5 inches (1 1.4 cm) for male (top), 4.4 inches (1 1.2 cm) for
female (bottom).

150

Mussels of the Midwest

Fatmucket

Lampsilis siliquoidea (Bames, 1823)

Other common names Grass mucket, black mucket, pugnose
mucket.

Key characters Elongate, moderately large, and thick shell,
yellow or tan with green rays; males bluntly pointed and com¬
pressed, females truncated and inflated.

Similar species Yellow sandshell, mucket, plain pocketbook,
rainbow, ellipse, pondmussel.

Description Shell elongate or elliptical, thin to thick, and
compressed (young individuals) to inflated. Anterior end
rounded, posterior end bluntly pointed (males) or truncated
(females). Dorsal and ventral margins usually straight. Umbos
only slightly elevated above the hinge line. Beak sculpture of six
to ten double-looped bars. Shell smooth, yellow or yellowish
green, sometimes tan or brown, with green rays of various widths
that may become indistinct in older individuals. Length to 5
inches (12.7 cm).

Pseudocardinal teeth divergent, elongated, or triangular, thin
to moderately thick; two in the left valve, one in the right
(occasionally with a thin, ridgelike tooth in front). Lateral teeth
straight to slightly curved, moderately long, and thin. Beak cavity
moderately deep. Nacre white or bluish white and iridescent
posteriorly.

Habitat Lakes and small to medium-sized streams in mud, sand,
or gravel.

Status Widespread and common throughout the Midwest.

Subfamily Lampsilinae

151

Lampsilis siliquoidea , INHS 3259. Sangamon River, Piatt County,
Illinois. Length: 3.6 inches (9.1 cm) for male (top), 3.4 inches (8.6 cm)
for female (bottom).

152

Mussels of the Midwest

Higgins eye

Lampsilis higginsi (Lea, 1857)

Other common names None.

Key characters Rounded to slightly elongate, thick, smooth,
and inflated shell, yellowish brown, with green rays; posterior
end bluntly pointed in males, truncated in females.

Similar species Pink mucket, mucket, fatmucket, plain pocket-
book, hickorynut.

Description Shell rounded to slightly elongate, solid, and
inflated. Anterior end rounded, posterior end bluntly pointed
(males) or truncated (females). Dorsal margin straight, ventral
margin straight to slightly curved. Umbos turned forward and
elevated above the hinge line. Beak sculpture, if visible, of three
or four double-looped ridges. Shell smooth, yellow, yellowish
green, or brown with green rays, obscure on some individuals.
Length to 4 inches (10.2 cm).

Pseudocardinal teeth triangular, thick, divergent; two in the
left valve, one in the right, occasionally with a smaller tubercular
tooth in front. Lateral teeth fairly long, moderately heavy, and
straight. Beak cavity deep. Nacre white, often tinged with cream
or salmon near the beak cavity, iridescent posteriorly.

Habitat Mississippi River and some of its larger northern
tributaries in gravel or sand.

Status Federally Endangered.

Subfamily Lampsilinae

153

Lampsilis higginsi, INHS 4602 and 1 1767. Mississippi River, Rock
Island County, Illinois. Length: 3.5 inches (8.9 cm) for male (top), 3.0
inches (7.6 cm) for female (bottom).

154

Mussels of the Midwest

Pink mucket

Lampsilis abrupta (Say, 1831)

Other common names Ohio mucket, tan mucket, square
mucket.

Key characters A rounded to slightly elongate shell, thick,
inflated, smooth, and yellowish brown; posterior end bluntly
pointed in males, truncated in females.

Similar species Higgins eye, mucket, fatmucket, plain pocket-
book, hickorynut.

Description Shell round to elliptical, solid, and inflated.

Anterior end rounded, posterior end bluntly pointed in males,
truncated in females. Dorsal margin straight, ventral margin
straight to slightly curved. Umbos turned forward and elevated
above the hinge line. Beak sculpture, if visible, of three or four
double-looped ridges. Shell smooth, yellow or yellowish green
and rayless or with faint green rays. Length to 4 inches (10.2 cm).

Pseudocardinal teeth triangular, thick, divergent; two in the
left valve, one in the right, occasionally with a smaller tubercular
tooth in front. Lateral teeth short, heavy, and relatively thick.
Beak cavity deep. Nacre pink or white, iridescent posteriorly.

Habitat The lower Mississippi and Ohio rivers and their larger
tributaries in gravel or sand.

Status Federally Endangered.

Subfamily Lampsilinae

155

Lampsilis abrupta , INHS 13809. Tennessee River, Hardin County,
Tennessee. Length: 3.6 inches (9.1 cm) for male (top), 2.9 inches (7.4
cm) for female (bottom).

156

Mussels of the Midwest

Plain pocketbook

Lampsilis cardium Rafinesque, 1820

Other common names Grandmaw, pocketbook.

Key characters Moderately thin, inflated, round to somewhat
squarish shell with the posterior end bluntly pointed in males and
truncated in females; smooth outer surface, yellow or tan with or
without green rays.

Similar species Fat pocketbook, pocketbook, mucket, pink
mucket, Higgins eye.

Description Shell large, round or somewhat quadrate, thin to
moderately thick (particularly in older individuals), and inflated.
Anterior end rounded, posterior end bluntly pointed (males) to
truncated (females). Dorsal and ventral margins straight to
curved. Umbos turned forward and elevated above the hinge line.
Beak sculpture of four or five elevated ridges. Periostracum
smooth, yellow or yellowish green, usually with numerous dark
green rays of various widths. Length to 7 inches (17.8 cm).

Pseudocardinal teeth relatively large, elevated, and rough¬
ened in young individuals, smoother in old specimens; two in the
left valve, one in the right. Lateral teeth straight to curved,
moderate in length, and striated. Beak cavity deep. Nacre white
or bluish white, occasionally pink or salmon, iridescent posteri¬
orly.

Habitat Small creeks to large rivers in mud, sand, or gravel.
Status Widespread and common throughout its range.

Subfamily Lampsilinae

157

Lampsilis cardium , INHS 8898. East Fork Spoon River, Stark County,
Illinois. Length: 4.0 inches (10.2 cm) for male (top), 3.5 inches (8.9 cm)
for female (bottom).

158

Mussels of the Midwest

Pocketbook

Lampsilis ovata (Say, 1817)

Other common names Sharp-ridged pocketbook, southern
pocketbook, grandmaw.

Key characters A round or oblong shell, inflated, posterior end
bluntly pointed in males and truncated in females; prominent,
sharply angled posterior ridge; outer surface smooth, yellow or
tan, and usually rayless except on the posterior slope.

Similar species Plain pocketbook, mucket, fat pocketbook, pink
mucket.

Description Similar in shape to the plain pocketbook. Shell
relatively large, rounded or oval, thin to moderately thick, and
inflated. Anterior end rounded, posterior end bluntly pointed in
males, truncated in females. Dorsal margin straight, ventral
margin curved. Umbos elevated above the hinge line. Prominent,
sharply angled posterior ridge present. Shell smooth, yellow or
yellowish brown, darker on the posterior slope, with rays largely
absent in adults except for a few thin green lines on the umbos
and posterior slope. Length to 6 inches (15.2 cm).

Pseudocardinal teeth thick, compressed and elevated; two in
the left valve, one in the right. Lateral teeth curved and short.
Beak cavity large and deep. Nacre white, iridescent posteriorly.

Habitat Large rivers in coarse sand or gravel.

Status Rare in the Ohio River and some of its larger tributaries.
Endangered in Ohio. Likely extirpated from Illinois.

Subfamily Lampsilinae

159

Lampsilis ovata, INHS 1076 (Ohio River, Alexander County, Illinois) and
UIMNH Z-4021 (Duck River, Maury County, Tennessee). Length: 4.2
inches (10.7 cm) for male (top), 3.8 inches (9.7 cm) for female (bottom).

160

Mussels of the Midwest

Wavy-rayed lampmussel

Lamp silis fasciola Rafinesque, 1820

Other common name Wavy-lined lampmussel.

Key characters A rounded shell, moderately thick in adults,
yellow or yellowish green, with numerous thin wavy green rays.

Similar species Plain pocketbook, pocketbook.

Description Shell moderately thick, round or ovate, compressed
to inflated. Anterior end rounded, posterior end bluntly pointed in
males, truncated in females. Dorsal margin straight, ventral
margin curved. Umbos only slightly elevated above the hinge
line. Beak sculpture of three to five indistinct wavy ridges. Shell
smooth, yellow or yellowish green, with numerous thin, wavy
green rays. Length to 3.5 inches (8.9 cm).

Pseudocardinal teeth triangular, short, thick, and divergent;
two in the left valve, one in the right, occasionally with a smaller
tooth on either side. Lateral teeth short and straight or slightly
curved. Beak cavity moderately deep. Nacre white, iridescent
posteriorly.

Habitat Medium-sized streams in gravel riffles.

Status Widely distributed but uncommon in northern tributaries
of the Ohio River. Endangered in Illinois. Species of Special
Concern in Indiana and Michigan. Species of Special Interest in
Ohio.

Subfamily Lampsilinae

161

Lampsilis fasciola, INHS 8616. Salt Fork Vermilion River, Vermilion
County, Illinois. Length: 3.0 inches (7.6 cm) for male (top), 2.8 inches
(7.1 cm) for female (bottom).

162

Mussels of the Midwest

Snuffbox

Epioblasma triquetra (Rafinesque, 1 820)

Other common names None.

Key characters A triangular shell, relatively thick for its size
with a sharply defined, broadly expanded posterior slope. Yellow
or yellowish green with green rays, blotches, or chevron
markings.

Similar species Elktoe, deertoe, fawnsfoot.

Description Shell small, fairly solid, triangular (males) to
somewhat elongate (females) and inflated (particularly in
females). Anterior end rounded, posterior end truncated in males,
expanded in females. Dorsal and ventral margins straight to
slightly curved. Posterior ridge sharply angled, posterior slope
wide, expanded, and ribbed (especially in females). Umbos
swollen and slightly elevated above the hinge line. Beak sculp¬
ture of three or four faint, double-looped bars. Periostracum
yellow or yellowish green, with numerous dark green rays,
blotches or chevron-shaped markings. Length to 2.5 inches
(6.4 cm).

Pseudocardinal teeth elevated, roughened, relatively thin and
compressed; two in the left valve, two in the right, with the front
one being thinner and much smaller. Lateral teeth very short,
slightly curved, serrated, and elevated. Beak cavity fairly deep.
Nacre pearly white, iridescent posteriorly.

Habitat Medium to large rivers in clear, gravel riffles.

Status Widespread but rare throughout the Midwest. Federal
Candidate (Category 2). Endangered in Illinois, Indiana, Wiscon¬
sin, and Michigan. Threatened in Ohio. Rare in Missouri.

Subfamily Lampsilinae

163

Epioblasma triquetra, INHS 5808. Embarras River, Douglas County,
Illinois. Length: 2.4 inches (6.1 cm) for male (top), 1.9 inches (4.8 cm)
for female (bottom).

164

Mussels of the Midwest

Catspaw

Epioblasma obliquata (Rafinesque, 1820)

Other common names Peewee.

Key characters Males and females both yellowish brown or
brown but much different in shape. Males oblong and solid, with
a shallow sulcus along the posterior ridge from the umbo to the
ventral margin. Females rectangular, truncated, and inflated pos¬
teriorly with a finely grooved surface and serrated growth lines.

Similar species Northern riffleshell.

Description Shell small, solid, rectangular or quadrate in fe¬
males, oval and elongate in males, and moderately inflated. Ante¬
rior margin rounded, posterior margin bluntly pointed in males,
expanded, truncated, ribbed, and notched in females. Ventral
margin broadly curved in males, straight to slightly curved in
females. Umbos full, about even with the hinge line and directed
forward. Posterior ridge double, with a relatively wide sulcus or
depression between the ridges in males, depression sharp and
narrow in females. Posterior-ventral portion of the shell in fe¬
males inflated with fine grooves that radiate from the umbo to the
margin of the shell. Growth lines serrated on the edge in the pos¬
terior third of the shell in the female. Periostracum yellowish tan
or brown, with numerous fine green rays most evident in females.
Length to 2 inches (5.1 cm). Males much larger than females.

Pseudocardinal teeth wide, elevated, serrated, horizontal; two
in left valve, one in right with two smaller teeth on either side.
Lateral teeth short, straight to slightly curved, roughened; two in
left valve, one in right with a much smaller tooth below. Beak
cavity shallow. Nacre white to purple, iridescent posteriorly.

Habitat Medium to large rivers in gravel riffles.

Status Federally Endangered.

Subfamily Lampsilinae

165

Epioblasma obliquata, UIMNH Z-3767. Tennessee River, Lauderdale
County, Alabama. Length: 1.8 inches (4.6 cm) for male (top), 1.2 inches
(3.0 cm) for female (bottom).

166

Mussels of the Midwest

Tubercled blossom

Epioblasma torulosa (Rafinesque, 1820)

Other common names None.

Key characters Males and females yellowish brown with green
rays but much different in shape. Males oblong with a sulcus
running along the posterior ridge from the umbo to the ventral
margin. Females with a large expanded posterior end. Both with a
series of enlarged knobs running from the beaks and continuing
to the posterior-ventral margin.

Similar species Northern riffleshell, sheepnose, threehorn
wartyback.

Description Shell thick anteriorly, much thinner posteriorly,

• elongate, and inflated. Anterior margin rounded, posterior-ventral
margin broadly rounded or slightly truncated in females, indented
in males. Umbos low, somewhat turned forward. Beak sculpture
of two or three indistinct ridges, evident only in very young
shells. A row of large tubercles or knobs running from the beaks
and continuing to the posterior-ventral margin. A wide, shallow
sulcus or depression present between the row of knobs and the
posterior ridge. Periostracum yellowish brown with numerous
fine green rays, obscure in older shells. Length to 3 inches
(7.6 cm).

Pseudocardinal teeth triangular, divergent, and roughened;
two in the left valve, one in the right with two smaller teeth on
either side. Lateral teeth short, straight and roughened; two in the
left valve, one in the right with a much smaller tooth below. Beak
cavity moderate to shallow. Nacre white, iridescent posteriorly.

Habitat Medium to large rivers in gravel riffles.

Status Federally Endangered. Extirpated from the Midwest.

Subfamily Lampsilinae

167

Epioblasma torulosa , UIMNH Z-3947. Tennessee River, Lauderdale
County, Alabama. Length: 2.2 inches (5.6 cm) for male (top), 2.1 inches
(5.3 cm) for female (bottom).

168

Mussels of the Midwest

Northern riffleshell

Epioblasma rangiana (Lea, 1839)

Other common name White-mouth riffleshell.

Key characters Males and females yellowish brown or green
but much different in shape. Males oblong with a sulcus running
along the posterior ridge from the umbo to the ventral margin.
Females with a large expanded posterior end. Tubercles on the
lateral surface greatly reduced or absent.

Similar species Tubercled blossom.

Description Shell elongate, thick anteriorly, much thinner
posteriorly, and compressed. Anterior margin rounded, posterior-
ventral margin broadly rounded in females, indented in males.
Umbos low, somewhat turned forward. Tubercles or knobs on the
lateral surface greatly reduced or absent. A wide, shallow sulcus
or depression present between the posterior and medial ridges.
Periostracum yellowish brown with numerous fine green rays,
obscure in older shells. Length to 2 inches (5.1 cm).

Pseudocardinal teeth triangular, divergent, and roughened;
two in the left valve, one in the right, with two smaller teeth on
either side. Lateral teeth moderately long, straight, and rough¬
ened; two in the left valve, one in the right with a much smaller
tooth below. Beak cavity moderate to shallow. Nacre white,
iridescent posteriorly.

Habitat Medium to large rivers in gravel riffles.

Status Proposed for Federal Endangered status. Endangered in
Indiana, Michigan, and Ohio. Extirpated from Illinois.

Subfamily Lampsilinae

169

Epioblasma rangiana , INHS 1675. White River, Indiana. Length: 1.8
inches (4.6 cm) for both male (top) and female (bottom).

170

Mussels of the Midwest

Extinct species

Leafshell

Epioblasma flexuosa (Rafinesque, 1820)

Round combshell

Epioblasma personata (Say, 1829)

Tennessee riffleshell
Epioblasma propinqua (Lea, 1857)

Wabash riffleshell

Epioblasma sampsonii (Lea, 1861)

The four species of the genus Epioblasma listed above have not
been found alive in the Midwest in more than 75 years, and all
are currently considered extinct (Turgeon et al. 1988, Appendix
2). Three are illustrated here in the likelihood their shells may be
encountered while collecting along the banks of the Wabash and
Ohio rivers and their larger tributaries.

Subfamily Lampsilinae

171

From top to bottom: Epioblasma flexuosa, INHS
1747. Length: 2.6 inches (6.6 cm). Epioblasma
personata , INHS 1468. Ohio River. Length: 1.9
inches (4.8 cm). Epioblasma propinqua, INHS
3206. Length: 2.2 inches (5.6 cm).

172

Mussels of the Midwest

Fingernailclams and Peaclams

(Family Sphaeriidae)

Musculium, Pisidium, and Sphaerium

Other common names Pillclams, nutclams.

Key characters Small, whitish or cream-colored shell with
numerous, very fine concentric rows of elevated lines (striae)
covering the surface. The right valve has one cardinal tooth and
two pairs of lateral teeth. The left valve has two cardinal teeth
and two lateral teeth.

Similar species Asian clam.

Description Shell rounded to slightly oval and inflated. Anterior
and posterior margins rounded. Umbos centrally located and
slightly elevated above the hinge line. Periostracum whitish or
cream-colored, with numerous, very fine concentric rows of
elevated lines (striae) covering the surface of the shell. The
posterior end of the shell is longer in Sphaerium and Musculium ,
and just the reverse in Pisidium. Length to 0.5 inch (1.3 cm).

The right valve has one cardinal tooth and two pairs of
lateral teeth. The left valve has two cardinal teeth and two lateral
teeth. Beak cavity moderately deep. Nacre white.

Habitat Lakes and streams of all sizes in silt, mud, sand, or
gravel.

Status Little is known regarding the status of fingernailclams
and peaclams. They have disappeared from many streams where
they were formerly abundant (such as the Illinois River).

Family Sphaeriidae

173

Sphaeriidae, INHS 14999. Kishwaukee River, McHenry County, Illinois.
Length: 0.5 inch (1.3 cm).

174

Mussels of the Midwest

Asian clam

Corbicula fluminea (Muller, 1774)

Other common names Asiatic clam, Corbicula.

Key characters Relatively small, yellowish brown to black shell
with numerous, evenly spaced, concentric, elevated ridges on the
surface. Three cardinal teeth in each valve located below the
umbo. Paired lateral teeth in each valve, two on each side of the
umbo in the right valve, one on each side in the left. The presence
of serrated lateral teeth separate Corbicula from the fingernail-
clams.

Similar species Fingemailclam.

Description Shell rounded to slightly triangular and inflated.
Anterior and posterior margins rounded. Umbos high, centrally
located, and elevated above the hinge line. Periostracum yellow¬
ish brown to black with numerous concentric rows of elevated
lines covering the surface of the shell. Young shells with a purple
stripe on the umbo. Length to 1.5 inches (3.8 cm).

Three triangular cardinal teeth in each valve located directly
below the umbo. Two sets of lateral teeth in each valve, moder¬
ately long, straight, and serrated; paired in the right valve, one on
each side in the left. Beak cavity deep. Nacre white or purple and
highly polished outside of the pallial line.

Habitat Lakes and streams of all sizes in silt, mud, sand, or
gravel.

Status Widespread and common. Introduced.

Family Corbiculidae

175

Corbicula fluminea, INHS 7276. South Fork Sangamon River, Christian
County, Illinois. Length: 1.5 inches (3.8 cm).

176

Mussels of the Midwest

Zebra mussel

Dreissena polymorpha (Pallas, 1771)

Other common names None.

Key characters Relatively small, triangular, and elongate shells
with alternating cream and brown bands on the surface.

Similar species Dark falsemussel. See Marsden (1992) for
information on distinguishing between these two species.

Description Adults with a distinctively shaped, elongate,
triangular, and inflated shell. Highly variable with respect to
color as its scientific name polymorpha (many forms) indicates.
Most are white or cream-colored with jagged lateral brown to
black stripes or bands, which give the species its common name.
Some have longitudinal bands, and all-cream or all-black
individuals have been found. Length to 1.5 inches (3.8 cm).

No pseudocardinal or lateral teeth. A small shelf or septum
present at the anterior end forming a moderately deep beak
cavity. Nacre white and somewhat polished.

Habitat Lakes and streams of all sizes; attaches to rocks,
freshwater mussels, or almost any hard surface by gluelike fibers
called byssal threads.

Status Introduced into the Great Lakes from eastern Europe and
rapidly spreading throughout the United States.

Family Dreissenidae

Dreissena polymorpha attached to Potamilus alatus , INHS 13808. Lake
Erie, Ottawa County, Ohio. Length: 0.8 inch (2.0 cm).

IlMlIW

Literature Cited

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Burch, J.B. 1975. Freshwater Unionacean clams (Mollusca: Pelecypoda)
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Coker, R.E. 1919. Fresh-water mussels and mussel industries of the
United States. Bulletin of the U.S. Bureau of Fisheries 36. 89 pp.

Cummings, K.S., and J.M.K. Berlocher. 1990. The naiades or freshwater
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Hoeh, W.R. 1990. Phylogenetic relationships among eastern North
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Marsden, J.E. 1992. Standard protocols for monitoring and sampling
zebra mussels. Illinois Natural History Survey Biological Notes 138.

40 pp.

Matteson, M.R. 1953. Fresh-water mussels used by Illinoisan Indians of
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Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of Missouri.
Missouri Department of Conservation, Jefferson City, Missouri, vii +
270 pp.

Parmalee, P.W. 1967. The fresh-water mussels of Illinois. Illinois State
Museum, Popular Science Series 8. 108 pp.

Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons,
W.L. Pratt, C.F.E. Roper, A. Scheltema, F.G. Thompson, and J.D.
Williams. 1988. Common and scientific names of aquatic invertebrates
from the United States and Canada: Mollusks. American Fisheries
Society Special Publication 16. 277 pp.

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U.S. Fish and Wildlife Service (USFWS). 1990a. White cat’s paw
pearly mussel recovery plan. U.S. Fish & Wildlife Service, Twin Cities,
Minnesota. 42 pp.

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of plant taxa for listing as endangered or threatened species; notice of
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17.11 & 17.12. July 15, 1991.37 pp.

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candidate review for listing as endangered or threatened species,
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van der Schalie, H. 1941. Fresh water mussels. Pages 61-67 in J.K.
Jacobson, ed. How to study and collect shells (a symposium). The
American Malacological Union, 1974. 107 pp.

Additional Reading

Illinois

Baker, F.C. 1898. The Mollusca of the Chicago area, Part I: The
Pelecypoda. Bulletin of the Chicago Academy of Sciences 3(1): 1-130 +
27 plates.

- 1906. A catalogue of the Mollusca of Illinois. Bulletin of the

Illinois State Laboratory of Natural History 7(6):53-136 + 1 map.

- 1922. The molluscan fauna of the Big Vermilion River, Illinois.

With special reference to its modification as the result of pollution by
sewage and manufacturing wastes. Illinois Biological Monographs
7(2): 105-224 + 15 plates.

- 1926. The naiad fauna of the Rock River system: A study of the

law of stream distribution. Transactions of the Illinois State Academy of
Science 19:103-112.

Cummings, K.S. 1991. The Aquatic Mollusca of Illinois. Pages 429-439
in L.M. Page and M.R. Jeffords, eds. Our Living Heritage: The Biologi¬
cal Resources of Illinois. Illinois Natural History Survey Bulletin
34(4):357-477.

Parmalee, P.W. 1967. The fresh-water mussels of Illinois. Illinois State
Museum Popular Science Series 8. 108 pp.

Schanzle, R.W., and K.S. Cummings. 1991. A survey of the freshwater
mussels (Bivalvia: Unionidae) of the Sangamon River basin, Illinois.
Illinois Natural History Survey Biological Notes 137. 25 pp.

Starrett, W.C. 1971. A survey of the mussels (Unionacea) of the
Illinois River: a polluted stream. Illinois Natural History Survey Bulletin
30(5):267-403.

Strode, W.S. 1892. The Unionidae of Spoon River, Fulton County,
Illinois. American Naturalist 26:495-501.

Suloway, L. 1981. The unionid (Mollusca: Bivalvia) fauna of the Kan¬
kakee River in Illinois. American Midland Naturalist 105(2):233-239.

182

M ussels of the Midwest

Suloway, L., J.J. Suloway, and E.E. Herricks. 1981. Changes in the
freshwater mussel (Mollusca: Pelecypoda: Unionidae) fauna of the
Kaskaskia River, Illinois, with emphasis on the effects of impoundment.
Transactions of the Illinois State Academy of Science 74(l/2):79-90.

Wilson, C.B., and H.W. Clark. 1912. The mussel fauna of the
Kankakee basin. Report and Special Papers of the U.S. Fish Commis¬
sion, 1911. 52 pp. -t- 1 map. [Issued separately as U.S. Bureau of
Fisheries Document 758],

Indiana

Call, R.E. 1900. A descriptive illustrated catalogue of the Mollusca of
Indiana. 24th Annual Report of the Indiana Department of Geology and
Natural Resources, 1899. 200 pp. + 78 plates.

Cummings, K.S., and J.M.K. Berlocher. 1990. The naiades or freshwater
mussels (Bivalvia: Unionidae) of the Tippecanoe River, Indiana.
Malacological Review 23( 1— 2):83— 98.

Daniels, L.E. 1903. A check list of Indiana Mollusca, with localities.
26th Annual Report of the Indiana Geological Survey, 1902. 23 pp.

Goodrich, C., and H. van der Schalie. 1944. A revision of the Mollusca
of Indiana. American Midland Naturalist 32(2):257-326.

Harmon, J.L. 1989. Freshwater bivalve mollusks (Bivalvia: Unionidae)
of Graham Creek, a small southeastern Indiana stream. Malacology Data
Net 2(5-6): 113-121.

- 1992. Naiades (Bivalvia: Unionidae) of Sugar Creek, East Fork

White River Drainage, in central Indiana. Malacology Data Net 3(1^1):
31-42.

Krumholz, L.A., R.E. Bingham, and E.R. Meyer. 1970. A survey of the
commercially valuable mussels of the Wabash and White Rivers of
Indiana. Proceedings of the Indiana Academy of Science 79:205-226.

Meyer, E.R. 1974. Unionid mussels of the Wabash, White, and East
Fork White Rivers, Indiana. Virginia Journal of Science 25(l):20-25.

Taylor, R.W. 1982. The freshwater mussels (naiads) of Big Indian
Creek, a small southern Indiana tributary of the Ohio River (Bivalvia:
Unionidae). Nautilus 96(2):66-68.

Additional Reading

183

Weilbaker, C., C.D. Baker, B.J. Forsyth, C.M. Christenson, and R.W.
Taylor. 1985. The freshwater naiads, Bivalvia: Unionidae, of the Blue
River, a Southern Indiana tributary of the Ohio River. Proceedings of the
Indiana Academy of Science 94:687-691.

Iowa

Keyes, C.R. 1888. An annotated catalogue of the Mollusca of Iowa.
Bulletin of the Essex Institute 20(4-6) :6 1-83.

Shimek, B. 1888. The Mollusca of eastern Iowa. Iowa University Natural
History Bulletin 1:56-81.

- 1935. The effect of pollution on mollusks in Iowa. Nautilus

48(4): 109-1 11.

Witter, F.M. 1878. List of the shells of Iowa. Quarterly Journal of
Conchology 1878:385-394.

Michigan

Boss, K.J. 1964. Unionidae of Red Cedar River, Michigan. Nautilus
77(4): 11 7-1 18.

Burch, J.B., and C.M. Paterson. 1976. Key to the genera of freshwater
pelecypods (mussels and clams) of Michigan. Museum of Zoology,
University of Michigan Circular 4. 35 pp.

De Camp, W.H. 1881. List of shell-bearing Mollusca of Michigan. Kent
Scientific Institute, Grand Rapids, Michigan. 13 pp. + 1 plate.

Goodrich, C. 1932. The Mollusca of Michigan. Michigan Handbook
Series No. 5. University of Michigan Press, Ann Arbor, Michigan. 120
pp. + 7 plates.

Goodrich, C., and H. van der Schalie. 1932. 1. On an increase in the
naiad fauna of Saginaw Bay, Michigan. II. The naiad species of the
Great Lakes. Occasional Papers of the Museum of Zoology, University
of Michigan No. 238. 14 pp.

- 1939. Aquatic mollusks of the Upper Peninsula of Michigan.

Miscellaneous Publications 43, Museum of Zoology, University of
Michigan. 45 pp.

184

Mussels of the Midwest

Hoeh, W.R., and R.J. Trdan. 1984. The freshwater mussels (Pelecypoda:
Unionidae) of the Upper Tittabawassee River drainage, Michigan.
Malacological Review 1 7( 1— 2):97 — 98.

- 1985. Freshwater mussels (Pelecypoda: Unionidae) of the major

tributaries of the St. Clair River, Michigan. Malacological Review
1 8(1/2): 1 15-1 16.

Strayer, D.L. 1979. Some recent collections of mussels from Southeast¬
ern Michigan. Malacological Review 1 2( 1— 2):93— 95.

- 1980. The freshwater mussels (Bivalvia: Unionidae) of the

Clinton River, Michigan, with comments on man’s impact on the fauna,
1870-1978. Nautilus 94(4): 142-149.

van der Schalie, H. 1936. The naiad fauna of the St. Joseph River
drainage in Southwestern Michigan. American Midland Naturalist
17(2):523-527.

- 1938. The naiad fauna of the Huron River, in southeastern

Michigan. Miscellaneous Publications 40, Museum of Zoology,
University of Michigan. 83 pp.

- 1948. The commercially valuable mussels of the Grand River in

Michigan. Miscellaneous Publication 4, Michigan Department of
Conservation. 42 pp.

Walker, B. 1879. Catalogue of the shell-bearing Mollusca of Michigan.
Journal of Conchology 1879:325-337.

- 1892. The shell bearing Mollusca of Michigan. Nautilus 6(2):

13-19, 6(3):3 1—35, 6(4):42^17, 6(6):63-67.

- 1893. The shell bearing Mollusca of Michigan (cont.). Nautilus

6:135-141.

- (1894-1895). A review of our present knowledge of the

molluscan fauna of Michigan. Thomas Smith Press, Detroit, Michigan.

27 pp. [Reprinted in Sterkiana (1965)17:10-25.]

- 1898. The distribution of the Unionidae in Michigan. Privately

published by Bryant Walker, Detroit, Michigan. 23 pp.

Additional Reading

185

Winslow, M.L. 1917. An annotated list of shells from northern Michi¬
gan. Occasional Papers of the Museum of Zoology, University of
Michigan No. 42. 16 pp.

- 1926. A revised check list of Michigan Mollusca. Occasional

Papers of the Museum of Zoology, University of Michigan No. 181.

28 pp.

Minnesota

Cvancara, A.M. 1970. Mussels (Unionidae) of the Red River valley in
North Dakota and Minnesota, U.S.A. Malacologia 10(1 ):57— 92.

Dawley, C. 1947. Distribution of aquatic mollusks in Minnesota.
American Midland Naturalist 38:671-697.

Grant, U.S. 1888. Notes on the molluscan fauna of Minnesota. Geology
and Natural History Survey of Minnesota 16:481-484.

Wilson, C.B., and E. Danglade. 1914. The mussel fauna of central and
northern Minnesota. Report of the U.S. Commissioner of Fisheries for
1913. Appendix 5:1-6. [Issued separately as U.S. Bureau of Fisheries
Document 803].

Missouri

Buchanan, A.C. 1980. Mussels (Naiades) of the Meramec River Basin,
Missouri. Aquatic Series 17, Missouri Department of Conservation.

68 pp.

Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of Missouri.
Missouri Department of Conservation. Jefferson City, Missouri, vii +
270 pp.

Utterback, W.I. 1915. The naiades of Missouri. American Midland
Naturalist 4:41-53,69-152, 189-204,244-273.

- 1916. The naiades of Missouri. American Midland Naturalist

4:31 1-327, 339-354, 387^100, 432-464.

Utterback, W.I., and E.M. Campbell. 1914. Mussel resources in
Missouri. Department of Commerce, Bureau of Fisheries Circular 10.

6 pp.

186

Mussels of the Midwest

Warren, R.E. 1991. Ozarkian fresh-water mussels (Unionoidea) in the
upper Eleven Point River, Missouri. American Malacological Bulletin
8(2): 131—137.

Ohio

Anthony, J.G. 1844. Collection of the terrestrial and fluviatile shells of
Ohio. Proceedings of the Academy of Natural Sciences of Philadelphia
2( 1 ):6 — 7.

Clark, C.F. 1977. The freshwater naiades of Ohio. Part I: St. Joseph
River of the Maumee. Sterkiana 65-66:14-36.

- 1987. The freshwater naiads of Ohio, Part V, Wabash River

drainage of Ohio. Malacology Data Net 2(1-2): 19-37.

Clark, H.W., and C.B. Wilson. 1912. The mussel fauna of the Maumee
River. Report and Special Papers of the U.S. Fish Commission, 1911.

72 pp. [Issued separately as U.S. Bureau of Fisheries Document 757].

Dean, G.W. 1890. Distribution of Unionidae in the three rivers,
Mahoning, Cuyahoga and Tuscarawas. Nautilus 4(2):20-21.

Hoggarth, M.A. 1990. The Unionidae of the Chagrin River: The
remnant of a molluscan fauna. Ohio Journal of Science 90(5): 168-170.

Lewis, J. 1877. Unionidae of Ohio and Alabama. Proceedings of the
Academy of Natural Sciences of Philadelphia 29:26-36.

Sterki, V. 1907. A preliminary catalogue of the land and fresh-water
Mollusca of Ohio. Proceedings of the Ohio State Academy of Science
4(8):367-402.

Watters, G.T. 1992. Distribution of the Unionidae in South Central
Ohio. Malacology Data Net 3(1^4):56-90.

Wisconsin

Baker, F.C. 1928. The fresh water Mollusca of Wisconsin. Part II.
Pelecypoda. Bulletin of the Wisconsin Geological and Natural History
Survey, vol. 70, No. 2. University of Wisconsin, vi + 495 pp.

Chadwick, G.H. 1905. List of Wisconsin shells. Nautilus 19(5):57-60.

Additional Reading

187

- 1906. List of Wisconsin shells (cont.). Nautilus 20(2):22-24.

Flowers, W. 1975. Notes on the current status of Wisconsin Unionidae.
Sterkiana 57:40-42.

Lapham, I. A. 1852. Catalogue of the Mollusca of Wisconsin. Transac¬
tions of the Wisconsin State Agricultural Society 2:367-370.

- 1860. List of the shells of Wisconsin. Proceedings of the

Academy of Natural Sciences of Philadelphia 12:154-156.

Mathiak, H.A. 1979. A river survey of the unionid mussels of Wiscon¬
sin 1973-1977. Sand Shell Press, Horicon, Wisconsin. 75 pp.

Morrison, J.P.E. 1932. A report on the Mollusca of the northeastern
Wisconsin lake district. Transactions of the Wisconsin Academy of
Sciences, Arts and Letters 27:359-396.

Roy, E.C. Jr. 1963. Checklist of Pleistocene and living Mollusca of
Wisconsin. Sterkiana 10:5-21.

Stern, E.M. 1990. An illustrated key to the freshwater mussels
(Bivalvia: Unionidae) of Wisconsin. Reports of the Museum of Natural
History No. 20. University of Wisconsin-Stevens Point. 75 pp.

Mississippi River

Scarpino, P.V. 1985. Great River. An environmental history of the
Upper Mississippi, 1890-1950. University of Missouri Press, Columbia,
Missouri, viii + 219 pp.

van der Schalie, H., and A. van der Schalie. 1950. The mussels of the
Mississippi River. American Midland Naturalist 44(2)448-466.

Ohio River

Rafinesque, C.S. 1820. Monographic des coquilles bivalves fluviatiles
de la Riviere Ohio, contenant douze genres et soixante-huit especes.
Annales Generates des Sciences Physiques, Bruxelles 5(13):287-322 +
2 plates.

Taylor, R.W. 1989. Changes in freshwater mussel populations of the
Ohio River: 1,000 BP to recent times. Ohio Journal of Science
89(5): 188-191.

188

Mussels of the Midwest

Williams, J.C., and G.A. Schuster. 1989. Freshwater mussel investiga¬
tions of the Ohio River, mile 317.0 to mile 981.0. Kentucky Department
of Fish and Wildlife Resources, Division of Fisheries, Frankfort,
Kentucky. 57 pp.

Use of Mussels by Native Americans

Baker, F.C. 1930. The use of animal life by the mound-building Indians
of Illinois. Transactions of the Illinois State Academy of Science 22:41-
59 + 6 plates.

Matteson, M.R. 1953. Fresh-water mussels used by Illinoisan Indians of
the Hopewell culture. Nautilus 66(4): 130-1 38, 67( 1 ):25— 26.

- 1958. Analysis of an environment as suggested by shells of

fresh-water mussels discarded by Indians of Illinois. Transactions of the
Illinois State Academy of Science 5 1 (3 — 4):8— 1 3.

- 1959. An analysis of the shells of fresh-water mussels gathered

by Indians in southwestern Illinois. Transactions of the Illinois State
Academy of Science 52(l-2):52-58.

Murray, H.D. 1981. Unionids from Indian sites in McMullen and Live
Oak Counties, Texas. Bulletin of the American Malacological Union
1981:10-11.

Ortmann, A.E. 1909. Unionidae from an Indian garbage heap. Nautilus
23(1): 1 1—15.

Parmalee, P.W., A. A. Paloumpis, and N. Wilson. 1972. Animals utilized
by woodland peoples occupying the Apple Creek site, Illinois. Illinois
State Museum Reports of Investigations 23. 62 pp.

Parmalee, P.W., and A.E. Bogan. 1986. Molluscan remains from
aboriginal middens at the Clinch River breeder reactor plant site, Roane
County, Tennessee. American Malacological Bulletin 4(l):25-37.

Parmalee, P.W., and W.E. Klippel. 1986. A prehistoric aboriginal
freshwater mussel assemblage from the Duck River in Middle Tennes¬
see. Nautilus 100(4): 134-140.

Parmalee, P.W., W.E. Klippel, and A.E. Bogan. 1982. Aboriginal and
modem freshwater mussel assemblages (Pelecypoda: Unionidae) from
the Chickamauga Reservoir, Tennessee. Brimleyana 8:75-90.

Additional Reading

189

Stansbery, D.H. 1966. Utilization of naiads by prehistoric man in the
Ohio Valley. American Malacological Union Incorporated Annual
Reports 32:4 1 —43.

Taylor, R.W. 1982. Mollusk shells associated with evidence of
habitation by prehistoric Native Americans in a Hardin County,
Kentucky cave. Transactions of the Kentucky Academy of Science
43(3 — 4): 155—157.

Taylor, R.W., and B.D. Spurlock. 1982. The changing Ohio River
naiad fauna: A comparison of early Indian middens with today. Nautilus
96(2):49— 51.

Theler, J.L. 1991. Aboriginal utilization of freshwater mussels at the
Azatlan site, Wisconsin. Pages 315-332 in J.R. Purdue, W.E. Klippel,
and B.W. Styles, eds. Beamers, bobwhites, and blue-points. Tributes to
the career of Paul W. Parmalee. Illinois State Museum Scientific Papers
No. 23 and the University of Tennessee Department of Anthropology
Report of Investigations No. 52. ix + 436 pp.

Index

Actinonaias ligamentina 104

Alasmidonta marginata 84

Alasmidonta viridis 86

Amblema plicata 40

Anodonta grandis 78

Anodonta imbecillis 74

Anodonta suborbiculata 76

Anodontoides ferussacianus 80

Arcidens confragosus 88

Asian clam 174

Asiatic clam 174

Bald-pate 24

Banana shell 148

Bank climber 148

Bastard 88

Bean shell 142

Black creek shell 146

Black mucket 150

Black pocketbook 88

Black sand mussel 136

Black sandshell 136

Bleufer 126

Blooper 126

Blue ham 66

Blue hen 126

Blue mucket 126

Blue-point 40

Board 24

Brass mucket 104

Buckhom 26

Bullhead 50

Bullnose 58

Butterfly 106

Catspaw 164

Chestnut shell 108

Clubshell 56

Common pondmussel 138

Corbicula 174

Corbicula fluminea 174

Cottonmouth 120
Cracking pearlymussel 70
Creek heelsplitter 96
Creeper 82, 148
Cumberlandia monodonta 22
Cyclonaias tuberculata 48
Cylinder 80
Cylindrical papershell 80
Cyprogenia stegaria 1 02
Deerhom 48,114
Deertoe 114

Dreissena polymorpha 176
Eastern fanshell 102
Ebonyshell 42
Eggshell 108
Elephant-ear 66, 92
Elktoe 84

Ellipsaria lineolata 106
Ellipse 140
Elliptio crassidens 66
Elliptio dilatata 68
Epioblasma flexuosa 170
Epioblasma obliquata 164
Epioblasma per sonata 1 70
Epioblasma propinqua 170
Epioblasma rangiana 168
Epioblasma sampsonii 170
Epioblasma torulosa 166
Epioblasma triquetra 1 62
False mapleleaf 28
Fanshell 102
Fat pocketbook 128
Fatmucket 150
Fawnsfoot 116
Fingemailclam 172
Flat floater 76
Flat pigtoe 58
Floater 78
Fluted-shell 94

192

Mussels of the Midwest

Fluter 40

Fragile heelsplitter 122
Fragile papershell 120
Fusconaia ehena 42
Fusconaia flava 46
Fusconaia subrotunda 44
Giant floater 78
Glassyback 108
Golf stick 112
Grandmaw 88, 128, 156, 158
Grass mucket 104,150
Hackle-back 92
Hatchet-back 124
Heelsplitter 76
Hemistena lata 70
Hickory nut shell 28
Hickorynut 108
Higgins eye 152
Hogshell 78
Honest John 136
Horn shell 72
Homy back 100

Kidneyshell 98
Knobbed rock shell 34
Lady finger 68
Lady’s slipper 136
Lampsilis abrupta 154
Lamp silis car dium 156
Lampsilis fasciola 160
Lampsilis higginsi 152
Lampsilis ovata 158
Lampsilis siliquoidea 150
Lampsilis teres 148
Lasmigona complanata 92
Lasmigona compressa 96
Lasmigona costata 94
Leafshell 170
Leptodea fragilis 120
Leptodea leptodon 1 1 8
Ligumia recta 1 36
Ligumia subrostrata 138
Lilliput 130
Little pocketbook 1 16
Little purple 132
Little spectaclecase 146

Long John 136

Long-solid 44

Luster shell 148

Mapleleaf 30

Megalonaias nervosa 24

Missouri mapleleaf 48

Monkeyface 34

Mucket 104

Mule’s ear 66

Musculium 172

Narrow papershell 118

Nodule shell 36

Northern clubshell 56

Northern riffleshell 168

Nutclam 172

Obliquaria reflexa 100

Obovaria olivaria 108

Obovaria retusa 112

Obovaria subrotunda 1 1 0

Ohio fanshell 102

Ohio mucket 154

Ohio pigtoe 62

Orange-foot pimpleback 54

Orange-footed pearlymussel 54

Pancake 92, 124

Paper floater 74

Paper pondshell 74

Papershell 74, 78, 120, 122

Peaclam 172

Pee wee 164

Peanut 26

Pigtoe 44, 46, 60, 62

Pillclam 172

Pimpleback 36, 38, 102

Pink heelsplitter 124

Pink mucket 154

Pink papershell 122

Pink pigtoe 58, 64

Pisidium 172

Pistolgrip 26

Plain pocketbook 156

Plethobasus cicatricosus 52

Plethobasus cooperianus 54

Plethobasus cyphyus 50

Pleurobema clava 56

Index

193

Pleurobema coccineum 58
Pleurobema cordatum 62
Pleurobema plenum 60
Pleurobema rubrum 64
Pocketbook 128, 156, 158
Pondhom 72
Pondmussel 138
Potamilus alatus 124
Pot ami l us capax 1 2 8
Potamilus ohiensis 1 22
Potamilus purpuratus 126
Ptychobranchus fasciolaris 98
Pugnose mucket 1 50
Purple heelsplitter 124
Purple lilliput 132
Purple pimpleback 48
Purple pocketbook 126
Purple wartyback 48
Purple-tip 40
Pyganodon grandis 78
Pyramid pigtoe 64
Quadrula cylindrica 32
Quadrula fragosa 28
Quadrula metanevra 34
Quadrula nodulata 36
Quadrula pustulosa 38
Quadrula quadrula 30
Queen 88
Rabbitsfoot 32
Rainbow 144
Rainbow shell 144
Rayed bean 142
Razorback 92
Ring pink 112
Ringed wartyback 102
Rock-pocketbook 88
Rockshell 88
Rough pigtoe 60
Round combshell 170
Round hickorynut 110
Round pigtoe 58
Round-solid 44
Salamander mussel 90
Sand clam 148
Sand mussel 94

Scaleshell 118
Sharp-ridged pocketbook 158
Sheepnose 50
Simpsonaias ambigua 90
Simpson’s shell 90
Slippershell mussel 86
Slopbucket 78
Slough sandshell 78
Sloughfoot 82
Smooth cob shell 32
Smooth minishell 90
Snuffbox 162
Solid pigtoe 58
Southern pocketbook 158
Sow’s ear 136
Spectaclecase 22
Spectaclecase mussel 32
Sphaeriidae 172
Sphaerium 172
Spike 68

Square mucket 154
Squawfoot 82, 94
Steamboat mucket 104
Stout floater 78
Strange floater 82
Stranger 30
Strophitus undulatus 82
Tan mucket 154
Tennessee riffleshell 170
Texas lilliput 134
Three dot 1 00
Three knot 100
Threehom wartyback 100
Threeridge 40
Toxolasma lividus 132
Toxolasma parvus 130
Toxolasma texasensis 134
Tritogonia verrucosa 26
Truncilla donaciformis 116
Truncilla truncata 114
Tubercled blossom 166
Turkey wing 26
Two-homed pocketbook 36
Uniomerus tetralasmus 72
Utterbackia imbecillis 74

194

Mussels of the Midwest

Venustaconcha ellipsiformis 140
Villosa fahalis 142

Villosa iris 144
Villosa lienosa 146
Wabash riffleshell 170
Wabash pigtoe 46
Warty pigtoe 38
Wartyback 36, 38
Washboard 24
Wavy-lined lampmussel 160
Wavy-rayed lampmussel 160
Western pondmussel 138
Western sand shell 138
White heelsplitter 92
White wartyback 52
White-mouth riffleshell 168
Winged mapleleaf 28
Winged orb shell 36
Winged pimpleback 36
Yellow sandshell 148
Zebra mussel 176